Electronic Slide Rule Calculators (1972-1979)
The Demise of the Slide Rule Industry
Including related calculators from the early 80's




Texas Instruments (TI) invented the first integrated circuit in 1958, courtesy of TI inventor Jack Kilby, and the hand-held calculator, a prototype called "Cal Tech", invented by TI's Jerry Merryman in 1967. However, the first hand-held calculator with scientific or 'slide rule' functions that was offered to the public was by Hewlett-Packard. The HP-35 was named by Bill Hewlett for the number of keys on the calculator and in 1972 was the beginning of the demise of the slide rule as we know it, Hewlett-Packard announced the HP-35 as a fast, extremely accurate electronic slide rule with a solid-state memory similar to that of a computer. Even though the introductory price was $395.00, engineers and engineering students flocked to the stores to get these (much like the iPod craze of today). Some students sold their cars to be able to afford one. However, because the exhorbitant manufacturing cost of the HP calculators put them out of reach of 90% of the general populace, the slide rule continued its popularity and usefulness for four more years. In ISRM's opinion, the official date of the death of the slide rule occurred on June 13, 1976 when Texas Instruments introduced the single chip TI-30 scientific slide rule calculator for $24.95 USD, which was below the cost of a comparable slide rule. There was no cost benefit to new students, technicians and engineers to buy a slide rule anymore, as everyone could afford the TI-30.
Video on the HP-35 from Hewlett-Packard

Slide Rule Calculators are defined as electronic calculators having the same functions as found on a Basic slide rule with A,B,C and D scales, minimally a multiply, divide and a square root key. Add in square, inverse (CI scale), and Sin, Cos and Tan trig functions and you have what was on Mannheim slide rules defined in 1850. This differentiates them from the four-function (+,-,x,/) calculators first introduced in 1970. Between 1970 and 1972 there were about 100 models of 4-function 'pocket' (some would be considered portable at least) calculators being manufactured or rebranded for the consumer market. When the slide rule calculator was first developed and made available to the common public in 1972, it was only natural to name these very pricey marvels for the tools they were about to replace.

In the July 1968 The Electronic Engineer, authors Hermann Schmid and David Busch wrote about: "An Electronic Digital Slide Rule - If This Hand-Sized Calculator Ever Becomes Commercial, the Conventional Slide Rule Will Become Another Museum Piece". The article goes on to say: "The Electronic Digital Slide Rule (EDSR) of the future not only will be smaller and easier to operate than the conventional slide rule, but it will also be more accurate.". The slide rule industry should have been paying attention.

What made the portable electronic calculator small enough to be as portable as a slide rule was the inventions of Large Scale Integration (LSI) by Ted Hoff of Intel and Integrated Circuits (ICs) by Jack Kilby of Texas Instruments. LSI/ICs stuffed several thousand transistors and diodes into a small low-power usage package needed for many operations of transendental functions. The Light-Emitting-Diode, so crucial to the miniaturization of the battery powered calculator, was invented in the mid-1960s by the US company Monsanto and marketed together with Hewlett Packard. Subsequent manufacturers of seven-segment displays for electronic calculators included Dialight, Fairchild, Litronix, Motorola and Texas Instruments.

Electronic semi-conductor manufacturers leveraged the 'SLIDE RULE' reference as a way to impart confidence in potential buyers that the new devices would do everything that a slide rule could do, but with more significant figures and automatic decimal point positioning, The advanced scientific slide rules added keys to save key strokes and having to calculate exponents and engineering exponentiation, as well as more memory functions. The cursor on a slide rule is analogous to the Memory keys on a calculator. When shiftable function keys were introduced, with the HP65, the number of functions doubled. You might say this analogous to complex 'duplex' slide rules, which had double the functions of a one-side slide rules.

The two very basic 1976 calculators on the right, a U.S. TI-1270 and a Japanese Canon 8M, both meet the minimum requirements to be a slide rule. The canon has a square root key and memory functions. The TI has square root, square and inverse functions.

Japan, Europe and the Soviet bloc started to produce their own Scientific 'slide rule' calculators (with an 'SR-' prefix) starting in 1976. but were behind in their marketing as compared to HP and TI. Once calculators became ingrained into the mainstream of education and technology for everyday use, the 'SLIDE RULE' tag was dropped in 1976 and 'SCIENTIFIC' or 'ADVANCED PROFESSIONAL CALCULATOR' became the standard model names for these multifunction calculators. Later brochures mentioned 'SLIDE RULE' until the Programmable Versions came out and reference to Personal Computing were being reinforced. By 1978 all conventional slide rules manufacturers were either out of business or switched to making other products than slide rules.

The downside to losing the slide rule, as we knew it, was now one needed to keep his batteries charged (which was found to be difficult in the field with calculators having built-in rechargable batteries). A contemporary slide rule can stay functional for over a century, but calculators can be killed by failed components or corroded batteries within a decade, although there was a period in the 1930's where celluloid was first used for cursors and crumbled within 15 years. Since rechargable NiCad batteries were part of the construction of calculators, users did not remove them when stored, and many calculators became unrepairable. It wasn't until about 1976 that 9V batteries replaced the NiCads in the calculators, followed by button cells when Liquid Crystal displays were introduced.

Secondly, and more importantly, a future generation would become numerically illiterate by losing the art of numeracy which was the empetus of the ISRM , with the support of members the Oughtred Society, to create the Slide Rule Loaner Program for Schools. Most of these specimens, listed in the chronological order of their release to the retail market, have red LED displays (or green Fluorescent displays). Liquid Crystal (LCD) displays appeared in 1979 after the model names went away from using SR, denoting 'Slide Rule', in favor of 'Scientific', with the exception of the TI SR-40-LCD and some green VFD (vacuum fluorescent displays) calculators out of Japan, Taiwan and Hong Kong. This gallery, for the most part, only displays electronic calculators that were marketed as SLIDE RULE CALCULATOR or ELECTRONIC SLIDE RULE or have reference to slide rules in their brochures or manuals. Another exception is the presence of a Square Root key. Texas Instruments held on to the SLIDE RULE tag longer than anyone else and their aggressive marketing lowered prices drastically within 5 years. There were a few Japanese calculator makers who used the SR prefix or suffix to denote a 'Scientific' calculator, but without reference to slide rules. The assumption being is that is why the USA did it in their translation and mimicing of U.S. technology. Other brands used "SR" to denote a 'Scientific' calculator with 'Rechargeable' batteries. I'll make a couple of exceptions and show calculators that when released were significant moments in history, like the 4- function Casio Mini, the first low cost pocket calculator in 1972. Review this collection of Articles on the History of Electronic Calculators at xnumber.com. First off ISRM would like to present the oldest electronic slide rule calculator in the museum, the HP9100A, shown on the right and below.


Hewlett-Packard 9100A Electronic Slide Rule sn816-00447
1968 - $4800.00 ($33,000 in today's money)


Although far from being a 'pocket' slide rule calculator, the 40 pound (18.1 kg) HP 9100A has the honor of being the very first Hewlett Packard calculator. This powerful desk top, portable calculator was introduced in 1968 and the high price made it so only corporate engineering departments could own one. Many engineers stood in line waiting to use it, in place of their slide rule. Some have called this the 1st personal computer, but it could only be programmed for mathematical operations. Bill Hewlett said, "If we had called it a computer, it would have been rejected by our customers' computer gurus because it didn't look like an IBM. We therefore decided to call it a calculator, and all such nonsense disappeared." The 9100A was the first scientific 'slide rule' calculator by the modern definition (i.e. trig, log/ln, and exponential functions), and was the beginning of Hewlett-Packard's long history of using reverse Polish notation entry on their calculators. The vey first paragraph on their sales brochure (3MB PDF) states:"Oriented to the engineering and scientific professions, the new hp 9100A Calculator contains all of the log, trig, and mathematical functions found on complex engineering slide rules - and more!". What is remarkable about the design, it uses NO integrated circuits, just diodes and transistors. The display is a 4" Cathode Ray Tube (CRT) as was used on their famous oscilliscopes. This unit was donated to ISRM by Alexey Davies, Boulder, Colorado, who obtained this in liquidation from his employer, Bell Telephone Labs (later AT&T).

Compucorp 322G 'Micro' Scientist Electronic Programmable Slide Rule
1971-1975 - $795 ($5465 in today's money)


Mr. Huang
ISRM Donor
The second important milestone was the development of ICs (Integrated Circuits) by Texas Instruments and made available to VARS (Value Added Re-Sellers). Compucorp designed what I believe to be the first PORTABLE Electronic Slide Rule in their Model 322 Micro Scientist, with advanced slide rule functions, and like the HP 9100A, was programmable.with two 80-step memories. The introduction in their manual states "The Micro Scientist is somewhat larger than a slide rule, but it's far more powerful and accurate than anything else its size." This is one of a "300" series of machines for different purposes. The journal "Electronics", for December 6, 1971, on their introduction, said of this series - "Each machine is "microprogramed" with MOS/LSI logic specifically for each application. ROMs produced by Texas Instruments and AMI to Compucorp specs control the keyboard functions pre-programed by the manufacturer. Groups of calculators bearing family names such as Statistician, Scientist, Accountant, and Treasurer, are thus tailored to the user." Under their own name and also Monroe, Sumlock, and IME, Compucorp Computer Design Corporation (later part of Wyle Laboratories of El Segundo, California) designed, manufactured and sold high specification electronic and hand-held calculators in the U.S.A. during the late 1960s and early 1970s. This 4 lb ruggedized calculator, with a cast aluminum housing, brought the electronic slide rule into the field. Preffered by surveyors. The machines included a battery compartment into which either disposable D-cell batteries, or rechargeable Nickel-Cadmium cells could be installed. An external power-pack provided ability to operate on AC power, as well as serving as a charger if NiCad batteries were installed in the machine. Due to the fragile nature of Nixie tube displays, the display technology used in the 300-series machines changed to the new Burroughs Panaplex II seven-segment planar gas-discharge 10+2 digit display. Calculations had a 13 digit precision. The Panaplex display was more durable, less expensive, and could be made smaller to fit within the confines of a 'handheld' device. More on Compucorp at www.oldcalculatormuseum.com/d-compucorp.html
Donated to ISRM by the Huang Collection.
Note 1: This is an educational historical resource intended for non-commercial use. All rights belong to the respective on-line sources and publications.
Note 2: If a Placard is shown with a specimen, that indicates that model (or an advertisement) will be shown in the physical exhibit along with the supportive images below,
Note 3: Some of the following images and manuals were provided by various contributing websites for the on-line gallery until we acquire our own specimens or scan the manuals and handbooks in the archives. Please support them. If you need a PDF of a manual not scanned yet, let us know and we'll increase the priority to get it in the queue.
Note 4: We are attempting to build exhibits with physical specimens, so if you have one of these, preferably one that you used in your career, and would like to donate it, we'll add your photo and bio and archive it for posterity. It always makes a specimen more interesting to know who used it. Thanks!



Compare slide rule scales with their
corresponding calculator keys

Longivity problems for collectors.

On the Left is KERCS (K&E Rotting Cursor Syndrom) found and on the right, corroded NiCad batteries. Either one can make the specimen worthless, especially with claculators, where metal contacts and traces may be dissolved by chemicals in the battery. Many times Cursores may be swapped from one model to another which is more desirable, and battery packs may be re-built with new batteries if the contacts are intact.

Dispay Types

See more about TI Displays


1968 Hewlett-Packard 9100A Desktop Electronic Slide Rule

ISRM would like to thank Joerg Woerner of datamath.org for his contribution of TI calculator photos, ephemera and descriptive text as well as his technical advice. ISRM would like to thank David G. Hicks of hpmuseum.org for his contribution of HP calculator photos, ephemera and descriptive text as well as his technical advice.

ISRM would like to especially thank Scott Reynolds of Vintage Calculators Inc (760-975-9503) for his technical advice in restoring these slide rule calculators and for his generous donation of numerous, and rare, calculators for this gallery and exhibit project.

Additionally we'd like to acknowledge the research, documents and images provided by the websites listed below.


Calculators Introduced in 1972

Supporting Advertisements for Prices and Dates:

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

Hewlett-Packard HP-35 Electronic Slide Rule V2 sn1249A-06787
February 1, 1972 - $395.00

Hewlett-Packard HP-35 ($395.00), the first pocket sized electronic calculator performing both logarithmic and trigonometric functions using Reverse Polish Notation (RPN). It was sold from 1972-1975. When the HP-45 was released in 1973, the price dropped to $295.00
Donated to ISRM by the Huang Collection..
Excerpt from HP-35 Owners Handbook, page i.

Popular Science Feb 1973 pg89

Manual (4.56Mb)



Mr. Huang
ISRM Donor

Texas Instruments TI-2500(B) sn458501
June 1972 - $149.95

The TI-2500 was called the Datamath . This four-function calculator becomes the most popular compliment to the slide rule for basic math functions. By September the next version is reduced to $119.95. By January 1974 the TI-2500B will sell for $69.95 and before the year is out the TI-2500-II will be available for $49.95.

Manual (2.32Mb)


Casio Mini, Japan, sn1349439
August 1972 - $59.95 (¥12,800)

The "Mini" from 1972 was Casio's first low-cost portable four-function calculator, and although it does not qualify as a 'slide rule' calculator, it shows the first attempts at making a pocket calculator accessible to the masses. It only has a 6-digit display using individual 7mm diameter, 12-lead, 7-segment fluorescent display tubes from NEC, which were cheaper than the US made red LEDs at the time. The display 'shifts' to the right passed the assumed decimal point, and provides a total of 12 digits. These were used in several early calculators from Japan. The Mini has no decimal point key, accepting only whole numbers. However, it will multiply and divide six-digit numbers to produce up to 12-digit results with an implied decimal point. For example, 2 Div 3 produces 0 in the main display, and 666666 when the shift key is pressed. Casio will add a square root key in a newer design by 1974.
Manual TBD



Sperry-Remington 663 sn2208198
December 1972 - $69.00

The mainframe computer company known as Sperry Rand, famous for the Univac "Super-Computer" marketed a line of Sperry Remington Rand calculators in the 1972- 1975 timeframe. This early calculator has a 6-Digit display that uses individual vacuum fluorescent tubes. It has a shift key for reading decimal points to the right and the zero is only half the size of the other numbers. Some of the same model numbers can be seen in radically different body styles. These were built by various Japanese companies like Casio and Olympus based on Sperry specifications. By 1976, Sperry was out of the calculator business to focus on their computer business. Like many of their competitors, they found profits in calculators hard to come by and left the business to the heavy-weights like TI, HP, Sharp, and Casio.

Manual (1.96Mb)


Warranty (2.25Mb)


Texas Instruments SR-10 Electronic Slide Rule V1 sn42777
November 1972 - $149.95

The announcement of TI's first Electronic Slide Rule Calculator (Version 1), caused those of us who bought an early TI-2500 to groan. The SR-10 had an X squared and a square root key along with 1/X and could do Engineering notation. Not as powerfule as the HP-35, as there are no trig functions, but it was more affordable. After this, no engineering student would ever buy just a four-function calculator. It was sold through 1975. Used AC Adaptor: AC9200, AC9130

Manual (3.2Mb)


Calculators Introduced in 1973

Supporting Advertisements for Prices and Dates:

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

Faber-Castell TR1
Slide Rule w/Calculator
1973 - $unknown

Faber-Castell TR1 (Der erste elektronische Taschen-Rechenstab) made by one of the premier slide rule manufacturers in Germany, attached has a pocket slide rule to the back of a similarly shaped four-function calculator. (The same needs I had when I bought the TI-2500 Datamath). Between the two sides, one could do all arithmetic and transcentental functions required. This hybrid model made more sense than the later TR2 as once F-C began to use the latest Texas Instruments chips there was a duplication of functions between the slide rule side and the calculator side. They used 4 large button cell NiCad 150 DK DEAC batteries with an external charger. F-C should be commended on their efforts to adapt to a changing world, but without in- house technology, they could not compete once TI started producing their own calc- ulators. F-C stopped making calculators and slide rules in 1976 and concentrated on other products. They are still a worldwide supplier of quality pencils.
Manual TBD
Large


Large
Scan of 1974 brochure donated by Dieter von Jezierski, Germany

WANTED
for Exhibit

ISRM 13.01.27.06

Exploded View

Sperry-Remington 809SR sn2110811
December 1973 - $??.??

The mainframe computer company known as Sperry Rand, famous for the Univac "Super-Computer" marketed a line of Sperry Remington Rand calculators in the 1972- 1975 timeframe. This early calculator, a re- branded Casio 10U, has an 8-Digit VFD display, powered by 5x AA batteries. It has a SQRT key which qualifies it as a slide rule calculator. You might think that 'SR' here stands for Sperry-Remington, but other than their SSR-8, no other model uses the suffix. 'SR' could also simlply mean 'Square Root'. By 1976, Sperry was out of the calculator market to focus on their computer business. Like many of their competitors, they found profits in calculators hard to come by and left the business to the heavy-weights like TI, HP, Sharp, and Casio.
Manual TBD

Texas Instruments SR-10 Electronic Slide Rule V2 sn505765
November 1973 - $89.95

The second version of TI's first Electronic Slide Rule Calculator (Version 2), can be identified by the model number being on the faceplate rather than on the LED bezel. There were some cost reductions. The SR-10 had an X squared and a square root key along with 1/X and could do Engineering notation. Not as powerful as the HP-35, as there are no trig functions, but it was more affordable. A third cost reduced version was sold in and through 1975. It removed the 7-segment display drivers and used a new calculator chip. Used AC Adaptor: AC9200, AC9130
Donated by Jeff Illsman of Longmont, Colorado, who worked for TI at the time this calculator was produced

Manual (3.2Mb)


V2 Internals

ISRM 12.06.20.xx
Commodore SR-36 Electronic Slide Rule Calculator sn05329
1973 - £49.95 ($119.88) in 1975 (exhange rate was 2.4)

The SR36, "The advanced electronic press-button slide rule". was one of the first scientific calculators made by Commodore with all the slide rule exponential and trig functions. The CPU is made by MOS Technologies, which was later bought by Commodore in 1976, and the other chips and red LEDs are supplied by Texas Instruments. It has 4x 3/4AA size Nicad batteries mounted in series at 4.8VDC. It has 36 single purpose keys. The first 1973 version had square keys with a raised oval, the entire button moved. This 1974 second version just has the oval move and is the transition to the other SR models. has The ad on the right was from an February 1975 (old artwork) New Scientist magazine which shows the square-oval keys on the upper 17 function keys. This specimen, found with its original Retail Box and Manual is the only proof ISRM has that shows that SR in the model number clearly meant SLIDE RULE. Later SR models dropped the referenece to slide rules in the manuals. By 1976, the term 'slide rule' was not used in Commodore's advertising or manuals as they were now thinking ahead toward programmable computers.

Manual (6.1Mb)


Feb 1975 New Scientist



ISRM 12.08.15.02
Hewlett-Packard HP-80 Electronic Business Slide Rule sn1249A-06787
1973 (through 1978) - $395.00

The HP-80 was HP's second handheld calculator. This calculator was designed for business rather than scientific/engineering. There were also slide rules being produced at the time, by K&E and Faber Castell that performed the same financial functions as this calculator. In addition to having different functions, the HP-80 was designed with a different philosophy. Whereas the HP-35 was designed for technical/mathematical users, the HP-80 was designed to be a problem solver that didn't require its users to know the formulas needed. Thus, the user could simply enter the parameters of a business problem and get an answer with a single keystroke. (In other words, the HP-35 user supplied the formulas, but on the HP-80, the calculator supplied them.)

Donated to ISRM by the Huang Collection..

Handbook to be scanned soon

Hewlett-Packard HP-45 Advanced Electronic Slide Rule sn1350A-91723
July 1973 - $395.00

The HP-45 was HP's third handheld electronic calculator and the second scientific model. It was the first pocket sized electronic calculator to have a shift key which doubled the computational power of the calculator. This is the last HP calculator that has comparisons with slide rules which is only mentioned in the manual. Early advertising brochures touted the HP-45 as doing "So much more. More than even our first 'electronic slide rule'!" It was sold from 1973-1976. Donated to ISRM by Scott Reynolds of Vintage Calculators Inc


Handbook to be scanned soon

Hewlett-Packard HP-35 Electronic Slide Rule V3 sn1249A-04461
July 1973 - $295-$195.00

The middle versions of the HP-35 had the '35' added to the bottom edge label, and because of the release of the HP-45 the price was reduced by half. More at MoHPC

Manual (4.56Mb)


Hewlett-Packard HP-65 sn1333A-02761
August 1973 - $795.00

This was the first programmable hand-held calculator and could save programs on magnetic strips. The HP-65 had up to 4 functions per key and had had 100 lines of space and used label addressing. It was the first HP pocket calculator with base conversions (but only octal and decimal). It was also the first to directly perform degrees.minutes seconds arithmetic (D.MS+ and D.MS-). In 1975 the American astronauts, swapped out their Pickett slide rules and calculated critical course-correction maneuvers on their HP-65 programmable hand-held during the rendezvous of the U.S. and Russian spacecraft. The Hp-65 had more computing power than the spacecraft, which was designed using 1960 technology.

Handbook to be scanned soon

ISRM 13.04.13.01
Melcor Answermath SR8 Electronic Slide Rule Calculator sn06528
1973 - $??.??

Melcor Electronics Corp. of Farmingdale, New York (USA) was one of the first US companies to enter the pocket calculator business, but they only made calculators for a few years. This model was their first with slide rule functions, sqr root, 1/X and X2. It sports 26, square two-color keys with rounded buttons, a red LED display which are powered by a 9V battery. Later models from Melcor were more obvious in their comparisons with slide rules and had better quality. This specimen has a lot of switch bounce either because the industry was just learning to make reliable contacts using printed circuit boards, or simply because it is 30 years old.
More info on Melcor

Manual (2.6MB)



ISRM 12.09.26.01
Melcor Model 400 Electronic Slide Rule Calculator sn21899
1973 - $??.??

Melcor Electronics Corp. of Farmingdale, New York (USA) was one of the first US companies to enter the pocket calculator business, but they only made calculators for a few years. This follow-on model is identical to the Answermath SR8, their first with slide rule functions, sqr root, 1/X and X2. It sports 26, square two-color keys with rounded buttons, a red LED display which are powered by a 9V battery. Later models from Melcor were more obvious in their comparisons with slide rules and had better quality. This specimen has a lot of switch bounce either because the industry was just learning to make reliable contacts using printed circuit boards, or simply because it is 30 years old.
More info on Melcor

Manual (2.6MB)



Texas Instruments SR-11 Slide Rule Calculator sn085270
September 1973 - $119.95

The SR-11 Slide Rule Calculator was basically an SR-10 that cost less to manufacture. No trig functions. The specimen shown here was made in USA, but notice the 'K' (slide) switch has a shroud. The same calculator made in Italy did not have the shroud, which hid the opening in the faceplate.

Manual (5.01Mb)


Italy vs USA

Bohn Omnitrex SR1 Slide Rule Calculator sn3707791-1
Circa 1973 - >$100

The US company Bohn Rex-Rotary the the past 40 years. (Div of VLM) distributed desktop calculators from Contex (Denmark) and this particular line of electronic calculators, which was made in Taiwan. This is one of the first Slide Rule Calculators with 9 individual green Vacuum Florescent Display (VFD) tubes. Page 2 of the manual claims : "...one of the most advanced Electronic Slide Rules available today..." . it is more suited to the desktop than being a portable like a slide rule. The archaic semi-RPN logic and size gave it a short life. The manufacturer was slow on the technology curve and was soon outmatched by the more advanced and lower cost products from TI and others. This specimen is New in the Box (NIB), and like most calculators with sealed rechargeable batteries requires new AA Ni Cads as these have begun to deteriorate over the last 40 years.

Manual (3.34Mb)


Warranty (900Kb)

Sperry-Remington 663 V2 sn3041831
December 1973 - $unknown

The mainframe computer company known as Sperry Rand, famous for the Univac "Super-Computer" marketed a line of Sperry Remington Rand calculators in the 1972- 1975 timeframe. This version (see the 1972 version above) calculator has a 6-Digit display that uses a single vacuum fluorescent tube. It has a shift key for reading decimal points to the right and the zero is only half the size of the other numbers. Some of the same model numbers can be seen in radically different body styles. These were built by various Japanese companies like Casio and Olympus based on Sperry specifications.

Manual (1.96Mb)


Warranty (2.25Mb)


Unisonic 737 Slide Rulette sn027208
Circa 1973 - $unknown

A 4-function calculator that is included simply because of its model name. It has 20 keys and uses 4 AA batteries to power the Vacuum Fluorescent Display (VFD). Unisonic Products Corporation was an American manufacturer established in 1972 as a distributor of consumer electronics. Although headquartered in New York City, Unisonic outsourced its manufacturing operations to various facilities in East Asia (especially in Hong Kong, South Korea, and Japan). Unisonic developed a variety of electronics, including calculators. Several of their first calculators had the trademark 'SLIDE RULETTE' even though they were missing the minimum requirement of a square root key. As the calculator industry became more competitive, they moved into game consoles and digital watches.
Manual TBD

ISRM 13.02.03.01
Unisonic 738 Slide Rulette sn027208
Circa 1973 - $unknown

A 20 key 4-function with memory calculator with a model name that identifies it as a slide rule. This model has the same keys as the Unisonic 737. Both models use 4 AA batteries to power the Vacuum Fluorescent Display (VFD). Unisonic Products Corp was an American manufacturer established in 1972 as a distributor of consumer electronics. Headquartered in New York City, Unisonic outsourced its manufacturing operations to various facilities in East Asia (especially in Hong Kong, South Korea, and Japan). Unisonic developed a variety of electronics, including calculators. Several of their first calculators had the trademark 'SLIDE RULETTE' even though they were missing the minimum requirement of a square root key. As the calculator industry became more competitive, they moved into game consoles and digital watches.
Manual TBD

Citizen 820SR Slide Rule Calculator sn406-13482
Circa 1973 - $unknown

This slide rule calculator was made by the Citizen Watch Company (parent Citizen Holdings Co., Ltd.) is a Japanese manufacturer of electronics, components, and in particular, watches. It has its headquarters in Nishi-Tokyo-shi, Tokyo. It was founded in 1918 as the Shokosha Watch Research Institute, and Citizen Watch Co., Ltd. itself was established in 1930. In the early 1970s, Citizen began to manufacture pocket calculators, which were widely used throughout Asia and Europe. Their biggest success was in the making of digital watches which better matched their original corporate mission, as there was less competition in that arena.They were already accustomed to the slide rule industry as they made chronograph watches with logarithmic scales. (Tachyometers).
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

ISRM 12.04.10.02
Texas Instruments SR-10 Version 2 sn505765
1973 - $89.95

There were internal changes and the SR-10 label moved from the display to the keyboard bezel. Major retail price reductions occurred in anticipation of the SR-50 release.
Donated to ISRM by Jeff Illsman, Longmont, Colorado

App Guide (3Mb)


OM US Manual (3.89Mb)


Litronix 2260 Slide Rule V1 sn52333
1973 - ~$100

Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line). Litronix Malaysia Sdn Bhd located in Penang was established in March 1972 with 7-segment light-emitting diode (LED) displays as initial products. Within a few years, the company expanded its product base into LED related consumer products such as LED watches, calculators and LED games. Litronix Malaysia was purchased by Siemens in 1976. This 'slide rule' model was an early version with tan case and small LED display.
Manual TBD


Commodore 774D Electronic Calculator sn17034
1973 - $??.??

The 774D four-function Electronic Calculator, assembled in USA is one of Commodore Business Machines early entries into the calculator market. It is much more compact that the rival Texas Instruments TI2500B and easily fits in a shirt pocket. It has red LEDs from TI and uses a 9V disposable battery.
Manual TBD


Commodore 798D Electronic Calculator sn17102
1973 - $??.??

The 798D Electronic Calculator, assembled in USA is one of Commodore Business Machines early models with the minimum slide rule function of a square root key. It is as compact and narrow as the 774D above, but is longer because of the additional keys and easily fits in a shirt pocket. It has red LEDs from TI and uses a 9V disposable battery.
Manual TBD


Calculators Introduced in 1974

Supporting Advertisements for Prices and Dates:

Team Electronics Ad Nov 1974, New Scientist Magazine

Nortex-Electronics Ad Nov 1974, Texas Monthly Magazine

The Brown And White, Lehigh, University, Bethlehem, PA April 1974

Radio Shack Ad, The Morning Record, Meriden, Connecticutt, Nov14, 1974

Faber-Castell 1975 Ad

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

ISRM 12.09.24.01
Faber-Castell TR2 Slide Rule w/Calculator sn0251209109
Circa 1974 - DM148

Faber-Castell TR2 (Der erste elektronische Taschen-Rechenstab) made by one of the premier slide rule manufacturers in Germany, attached has a pocket slide rule to the back of a similarly shaped 'slide rule' calculator with exponential functions. The first attempt at a hybrid was with the 1973 TR-1 which was only four functions. That model made more sense than the TR2 as once F-C began to use the latest Texas Instruments chips there was a duplication of functions between the slide rule side and the calculator side. They used 4 large button cell 150 DK DEAC NiCad batteries. F-C should be commended on their efforts to adapt to a changing world, but without in- house technology, they could not compete once TI started producing their own calc- ulators. F-C stopped making calculators and slide rules in 1976 and concentrated on other products. They are still a worldwide supplier of quality pencils.
Manual TBD

1975 Ad

Corvus 310 Calculator sn310-151267
July 1974 - $??.??

Corvus was the consumer division of the IC manufacturer MOSTEK. They introduced the Model 310 a basic four-function calculator with 20 keys including a square-root and percent key. It uses their MS5020A calculator circuit powered by 4AA batteries.to drive a red LED module made by Hewlett-Packard.
MOSTEK was founded in 1969 as a spin-off of Texas Instruments and engaged in the manufacturing and marketing of Metal Oxide Semiconductors and Large Scale Integration (MOS/LSI) integrated circuits. Already in May, 1970 MOSTEK started the development of the MK6010, the world's first "single-chip" calculator circuit for for Nippon Calculating Machine Company, better known under the brand Busicom. More about MOSTEK at Datamath.org

Manual (4.5Mb)


Archive -Need for exhibit
Corvus 411 Slide Rule Calculator With Memory
Sept 1974 - $89.95

Corvus was the consumer division of the IC manufacturer MOSTEK. As part of their initial line-up, they introduced this Slide Rule With Memory with 24 keys which had SQRT PI, 1/X, EE, and memory functions. It uses their MK50310N calculator circuit chip powered by 4AA batteries.to drive a red LED module made by Hewlett-Packard. This is a great example of a 'slide rule' as it was printed on the cover of the manual:

Manual (883Kb)


Need for Exhibit

ISRM 13.02.03.02
Litronix 2140 Slide Rule Calculator
1974 - $??.??

This 'slide rule' model was an early version with brown case and small LED display powered by 3 AA disposable batteries. It has all the minimum slide rule capabilities,, 1/X, X^2, SQRT, +/-, plus memory, less trig functions. This is otherwise a direct competitor to the TI SR-10. The Litronix 2240 would be released with the same layout but would be called 'Scientific' or "slide rule'.
Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line). Litronix Malaysia Sdn Bhd located in Penang was established in March 1972 with 7-segment light-emitting diode (LED) displays as initial products. Within a few years, the company expanded its product base into LED related consumer products such as LED watches, calculators and LED games. Litronix Malaysia was purchased by Siemens in 1976.
Manual TBD


Texas Instruments TI-2550 Memory Calculator sn036897
January 10, 1974 - $99.95

Roughly one year after the introduction of the famous TI-2500 alias Datamath the engineers at Texas Instruments added a full memory onto the calculator chip. Integrated into a housing similar to the wedge shape of the SR-11 it was named TI-2550. It uses TI power adaptor AC9130 with 3 AA nicads or 4 AA alkaline batteries. A close relative of the TI-2550 was sold through the American department store Montgomery Ward. Compare the TI-2550 with the P200.

Manual (2.7Mb)


Montgomery Ward P200 sn47X-035014
1974 - ~$79.95

The P200 could be easily identified as a close relative of the TI-2550. Both calculators use the same electronics, the same layout of the keyboard and even an identical mold for the housing bottom. The different look is achieved through a new mold for the upper half of the housing and a different style of the memory keys. The color of the housing is slightly different, too. This has a Texas Inst. model number TXI-8662A. It uses TI power adaptor AC9130 with 3 AA nicads or 4 AA alkaline batteries.
Donated to ISRM by Scott Reynolds, Vintage Calculators Inc. Hemet, CA

Manual (2.45Mb)


Aristo M36 Electronic Slide Rule sn2L013-0441
1974 - $unknown

Dennert & Pape (Aristo) was one of the world's premier suppliers of slide rules in Germany, and after reading the writing on the wall, stopped slide rule production and created their own line of electronic slide rules. The M36 is the 2nd calculator, and the 1st of their own design. It does not have any slide rule or transcendental functions but it was the start of an entire product line. This Basic 4-function calculators competited against the TI-2500 and others like it while they developed more complex calculators. It has red LED's from Hewlett-Packard and uses 3 AA batteries.
Manual TBD

Aristo M65 Electronic Slide Rule snF2LT04-0359
1974 - $unknown

Dennert & Pape (Aristo) was one of the world's premier suppliers of slide rules in Germany. They stopped slide rule production and created their own line of electronic slide rules. The M65 is their own 2nd generation design, thinner and trimmer than all the other makers slide rule calculators. It has the basic slide rule functions (Square root, 1/X, X squared) accessible via a function key and competes againts the Texas Instrument SR-50. It has red LED's from Hewlett-Packard and uses 3 AA batteries.
Manual TBD


Radio Shack EC-425 Electronic Slide Rule sn026912
November 1974 - $79.95

The Radio Shack (Tandy Corp) EC-425 is easily identified as a close relative of the TI SR-10, as is the Montgomery Ward P300. Both calculators use the same electronics, the same layout of the keyboard and even an identical mold for the housing bottom. The different look is achieved through a new mold for the upper half of the housing, shared with the Ward P300, and a different color of the function keys. The color of the plastic is different . It uses TI power adaptor AC9130. The early release of the EC-425 occured just in time for Christmas of 1974 in newspaper ads with at a sale price of $69.95, but did not appear in the RS catalog until 1975, with catalog number 65-632. This model did not appear in the 1976 RS catalog as Tandy went with other slide rule calculators made by Commodore and Rockwell which had better pricing.

Manual (3.6Mb)




Montgomery Ward P300 Slide Rule Calculator sn47X-026332
1974 - ~$99.95

This Montgomery Ward P300 aka TXI-8663A is another a close relative of the TI SR-10, as is the Radio Shaeck EC-425. Both calculators use the same electronics, the same layout of the keyboard and even an identical mold for the housing bottom. The different look is achieved through a new mold for the upper half of the housing, Shared with the Radio Shaeck EC-425, and a different color of the function keys. The color of the housing is slightly different,too. It uses TI power adaptor AC9130.
Manual TBD

ISRM 12.04.10.04
Texas Instruments SR-50 sn0447926
January 1974 - $169.95

The SR-50 Slide Rule Calculator finally has trig functions and a couple more keys for doing logarithms and fractional exponents. This starts a calculator pricing war with HP as this much less than the cost of an equivalent HP-35. The algebraic method, using the equal sign, is more comfortable with the buying public, than HP's RPN. By March of 1975 manufacturing costs are reduced bring it to $109.50.
Donated to ISRM by Jeff Illsman, Longmont, Colorado

Manual (5.45Mb)


Commodore Minuteman 3S (MM3S) Electronic Slide Rule Calculator
Mar 1974 - $59.95

This relatively compact calculator is one of Commodore's first models with the basic slide rule functions of square root and square. The major internal components (CPU, chips and red LEDs) are supplied by Texas Instruments. Three versions of the Minuteman 3 exist: the MM3 (4 function $39.95), the MM3P (with Percentage and Discount Key $54.95) and the MM3S (Square and Square root $59.95) as shown here. It has four 2/3AA Nicad batteries sealed in a 2 row tandem pattern. The 4x5 keyboard has minus and plus keys doubling up as equal keys. The 3 position switch has OFF-ON-K. The 'K' position allows a number to be entered and retained as a constant for series multiplation and division.
Manual TBD

Commodore SR-1400 Electronic Slide Rule Calculator
1974 - $99.95

This is Commodore's first scientific model which introduced nomenclature that Commodore used for most of these types: the "SR" prefix indicates a scientific model with slide rule functions. This calculator, which came in two faceplate variations, devotes one key to a function, so the user is faced with nearly 40 keys. This abundance of keys and functions beacame a trademark of Commodore's advanced models. This one sports red LEDs.
Manual TBD

Unisonic 1212 Slide Rulette sn027208
Circa 1974 - $unknown

A 4-function calculator that is included simply because of its model name. Unisonic Products Corporation was an American manufacturer established in 1972 as a distributor of consumer electronics. Although headquartered in New York City, Unisonic outsourced its manufacturing operations to various facilities in East Asia (especially in Hong Kong, South Korea, and Japan). Unisonic developed a variety of electronics, including calculators. Several of their first calculators had the trademark 'SLIDE RULETTE' even though they were missing the minimum requirement of a square root key. As the calculator industry became more competitive, they moved into game consoles and digital watches.
Manual TBD

Litronix 2250 Slide Rule sn101345
1974 - ~$100

Marked as being a 'Slide Rule', this calculator was made by Litronix, Inc., (Cupertino, CA), an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line). Litronix Malaysia Sdn Bhd located in Penang was established in March 1972 with 7-segment light-emitting diode (LED) displays as initial products. Within a few years, the company expanded its product base into LED related consumer products such as LED watches, calculators and LED games. Litronix Malaysia was purchased by Siemens in 1976.
In comparison with the 2260, the 2250 has parenthesis '(' and ')' keys in place of memory keys 'RM' and 'M'
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD


Litronix 2260 Slide Rule V2 sn50001
1974 - ~$100

This is an updated model of the Litronix (Cupertino, CA) 2260 slide rule. Compare with the tan versionreleased in 1973. This 'slide rule' model late version has a brown case, with shrouded keys and an LED display with digits twice the size. Of particular interest, this specimen has serial number 50001, the first in this series. Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line).
Manual TBD


Litronix 2280 Memory II sn103670
1974 - ~$100

This is four-function calculator with expanded memory functions by the Litronix company. It has the same packaging as the late 2260 slide rule model with a brown case, shrouded keys and a large LED digits. display with digits twice the size. Although there are no slide rule functions, it is a good example of how companies maximize tooling across product lines. Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line).
Manual TBD


Berkey 4030 Slide Rule Calculator sn0247165
1974 - $unknown

This USA made slide rule calculator by Berkey Photo Inc, was the most advanced of the other known related specimens from 1972, the Berkey-Omega 100, Berkey- Keystone 88 and 350 and Atlas-Rand 240 which were limited to 4-functions. Berkey calculators all use a Rockwell CPUs and a Burroughs Panaplex II amber gas-discharge display, normally only found in desktop calculators. The Rockwell chip in this unit has a 7423 date code

Berkey has been a camera manufacturer since its 1966 acquisition of the Keystone Camera Company, a producer of movie cameras and equipment. In 1968 Berkey began to sell amateur still cameras made by other firms, and the following year the Keystone Division commenced manufacturing such cameras itself. In 1972 they tried entering the new calculator market but lasted only until 1974. From 1970 to 1978, Berkey accounted for a tenth of the sales in the camera market in the United States,. In 1978, Berkey sold its camera division and thus abandoned this market.

Manual TBD

Rockwell 30R Slide Rule Memory sn221837
Circa 1974 - $unknown

This calculator, which has 'Slide Rule Memory' on the front edge, appeared to have been issued to a North American Rockwell (as U.S. company) employee as it has an asset tag on the back. Made in Great Britain by Rockwell International, Microelectronic Product Division. It uses a 9.0V DC battery. The display is an 8 digit red LED with bubble lens and ninth digit for minus sign and has four functions with percentages and four function memory. Register exchange, change sign, inverse, squares and square roots. The only thing missing to make it a perfect slide rule is a Pi key, but most technical people can remember 3.14159 which is all the accuracy anyone needs.
Manual TBD

ISRM 13.01.27.24
Rockwell 31R Slide Rule Memory sn151267
Circa 1974 - $unknown

This calculator, which has 'Slide Rule Memory' on the front edge, the same as the 30R, which was made in England. The 31R, however was assembled in Mexico, with US and Foreign parts, by Rockwell International, Microelectronic Product Division. It uses a 9.0V DC battery. The display is an 8 digit red LED with bubble lens and ninth digit for minus sign and has four functions with percentages and four function memory. Register exchange, change sign, inverse, squares and square roots. The only thing missing to make it a perfect slide rule is a Pi key, but most technical people can remember 3.14159 which is all the accuracy anyone needs.

Manual (6.0Mb)


Cover


Rockwell 61R Advanced Slide Rule sn163764
Circa 1974 - £29.95 (Nov 1975)

This calculator, which has 'Advanced Slide Rule' on the front edge, was made in Great Britain by Rockwell International, Microelectronic Product Division. It uses a 3.6V NiCad battery pack with a 6V charger. The display is an 8 digit blue VFD (Vacuum Flourescent Display) with a ninth digit cluster for minus sign and error indications. It has a shift keys and four function plus logs, trigs, powers, square root, change sign, register exchange, reciprocal, pi, data recovery and six function memory. Degree / radian switching. This one, unfortunately is INOP.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD
Landau Radio Ltd. Ad
Nov1975 New Scientist

ISRM 12.04.10.34
Sears Electronic Slide Rule, sn214649
Circa 1974 - $unknown

Sears and Roebuck ESR model 801.58770 was designed in the USA and has the same keyboard layout (and most likely the same circuit board) as the Rockwell Model 61R. It is an algebraic scientific calculator with 40 functions using 20 keys with a switch for radians or degrees. It uses 4 AA batteries. This specimen was assembled in Mexico.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc

Manual (960kb)


ISRM 12.04.10.33
Sears Electronic Slide Rule II, sn123528
Circa 1974 - $unknown

Sears and Roebuck ESR model 801.58780 was designed in the USA and has the same keyboard layout as the model 801-58770 but with reduced basic slide rule functions. It is an algebraic scientific calculator with 30 functions using 20 keys with a switch for radians or degrees. It uses 4 AA batteries and drives a green VFD readout. This specimen was assembled in Mexico.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc

Manual (4.26Mb)


Sears 10M, sn216498
Circa 1974 - $unknown

Sears and Roebuck 10M model 728-5825 was made in USA and was made by Rockwell. It is an algebraic calculator with the basic slide rule and memory functions. It has 3 AA rechargable nicads inside and requires an external charger. This specimen was made in the USA.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

Silver-Reed SR80 (Version 2) sn00007602
1974 - $unknown

Silver Reed Ltd. began operations as Marukoshi Knitting Machines Ltd. in Tokyo in the 1950s and in 1967 the company name was changed to Silver Seiko Ltd. It claims to be the first company to sell electronic home knitting machines as early as 1977, and, as as their technology, began selling rebranded calculators and electric typewriters. The SR80 has the minimal slide rule function of a sqr root key. the 1st version of the SR80's did not have it. It is most likely that the prefix 'SR' stands for 'Silver Reed', as another model, the SR82S (see example), has 'Slide Rule' printed on the faceplate. The suffix 'S' must stand for Scientific or Slide Rule, and the prefix 'SR' for the company intitials. This calculator uses 2 AA batteries driving a green VFD display. The instructions on the back are in German.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD


SR82S SlideRule


Sperry-Remington SSR-8 Scientific Slide Rule sn8021122
May 1974 - $99.95

One of the early scientific slide rule hand-held calculators using an 8 digit Vacuum Fluorescent Display VFD . The mainframe computer company known as Sperry Rand marketed a line of Sperry Remington Rand calculators in the 1972-1975 time frame, all made in Japan. It is physically identical to the Casio FX-10 Scientific Calculator of that period, with different colors. By 1976, Sperry abandoned the calculator business to focus on their computer business.
Manual TBD

Texas Instruments SR-16 Slide Rule Calculator sn038211
October 1974 - $99.95

The SR-16 Slide Rule Calculator, used the packaging size of the SR-10 but had extra keys for doing logarithims and fractional exponents, but no trig functions. Its novelty was quickly outmoded when the SR-50 was released 3 months later. The SR-16 is considered a rarity amongst collectors. It would return again in a year as the SR-16-II in a cheaper package.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc

Manual (4.4MB)


ISRM 13.07.02.01

APF Mark 23 Electronic Slide Rule Calculator snJ-019752
1974-1975 - $??

The APF (U.S. company) MARK 23 Electronic Slide Rule Calculator is an arithmetic calculator with 8 digits precision and algebraic logic. It has 9 functions, 20 keys and a VFD (vacuum fluorescent) display in a single tube. The power source is sealed battery pack using 3 AA NiCads, chargeable with a 4.5 DC source. The calculator was manufactured in Japan.

This specimen was found in its original retail box with a J.C. Pennys price tag on it. It is a another unique example of an electronic calculator being marketed for the slide rule users.


Manual (1.39MB)


Manual Cover

Sears Digi-matic SR-8 sn02261
1974- <$100

The Sears SR-8 Slide Rule Calculator is a with 8 digits precision and algebraic logic. It has 9 functions using 20 keys, all the functions required of a slide rule, and a VFD (vacuum fluorescent) display. The power source is sealed rechargeable NiCad batteries. This may have been manufactured by Bowmar - the inventor of the first "True-Pocket-Size" calculator, and assembled in Mexico.
Manual TBD

Rockwell 202 slide Rule sn176657
1974 - >$100

There is no doubt that this was 'slide rule' calculator with the printing on the display bezel. This classic Rockwell design is a little larger than most with 21 functions, 20 keys on 21 pivoting keys in the normal Rockwell colors. It has an 8+2 digit blue VFD display with a ninth digit (and intervening one) for the minus signs. Display input starts at the left rather than the normal right. The power source is four AA disposable Alkaline or rechargeable NiCad batteries. It was assembled in Mexico.
This is one of the first true Rockwell calculators. Although they had made ICs from the very early days it wasn't until Rockwell bought Unicom (in 1972) that they started their own brand. These "Transition Models" are renamed Unicom calculators.

Manual (4.73Mb)


Melcor SC-535 Electronic Slide Rule Calculator sn39340
1974 - $89.95

Melcor Electronics Corporation of Farmingdale, New York (USA) was one of the first US companies to enter the pocket calculator business. Like Bowmar, they were known for quality products but only made calculators for a few years. The first Melcor instruction manuals had a the picture of a Pickett slide rule on the cover (see the SC-635 and 645 examples). The SC-535, the first of the Scientific Calculators, has 18 functions, 37 keys and an 11 digit 7 segment LED (light-emitting diode) display. In order to provide more calculating time the first units had double the battery storage of later units. The power source was a pair of in-line sealed battery pack which was charged with an external DC 7.5V power supply. Each pack consists of 3x 1.5V cells and apparently the packs are connected in series. It was discontinued in 1975 when it was replaced by the SC-635, which only used one of the battery packs.
More info on Melcor
Manual TBD

Team Electronics Ad, Nov 4,1974,Lawrence-Journal, Louisiana


ISRM 12.09.12.01
Melcor SC-635 Electronic Slide Rule Calculator sn653172
1974/1975 - >$49.95 kit ($69.95 Assembled)

There is no doubt that this was a 'slide rule' alternative with the picture of the Pickett on the cover of the manual. Melcor Electronics Corporation of Farmingdale, New York (USA) was one of the first US companies to enter the pocket calculator business. Like Bowmar, they were known for quality products but only made calculators for a few years. To save money you get it in a kit and solder your own components. The SC-635 came out with a math error (just like the first HP-35) but it was not found until 50,000 units were produced. These were sold in 1975 at a discount and the corrected chip versions went to $99. The SC-635 has 26 functions, 40 keys and an LED (light-emitting diode) display, typical of calculators of this era. The power source is a unique in-line sealed battery pack consisting of 3x 3/4 size 1.2V Batteries.
More info on Melcor

Manual (3.07Mb)




Sinclair Scientific Electronic Slide Rule Calculator
April 1974 - >$29.95 kit ($69.95 Assembled)

This VERY SMALL calculator, designed by Clive Sinclair has 18 keys with 12 functions on a simple keyboard. It uses scientific notation having a 200 decade (step) range using reverse Polish notation (RPN). The red LED display has a5 digit mantissa, with 2 digit exponent, powered by 4 AAA batteries. This unit was offered in a kit form (like the Melcor calculator line). For people in Britain in the 1970s and 1980s Clive Sinclair was known as "the inventor of the pocket calculator". To reduce power consumption he used a method of pulsing the power to Texas Instruments chip every 1.7 microseconds to keep the operations alive using the internal capacitance to store the charge.
More info on the Sinclair Scientific Kit
Clive Sinclair and the Pocket calculator
Manual TBD



Mintron ESR-817 Electronic Slide Rule sn4065619
1974-1975 - $ ?

Mintron Electronic Slide Rule by Minsung Electronics, Ltd, Seoul, Korea. This specimen has 'SR' in the model name as well as saying 'Electronic Slide Rule' on the back label. It has 9 individual 7-segment LEDs, a rare design as cost reduced LED arrays and VFD's were already becoming popular, and is powered by 4 2/3AA NiCd batteries. Fortunately, it can use a Canon AC adaptor to charge the batteries, which have been replaced by new 400mAh NiCds. The internal MOS chips have a date code of 1974. This model was acquired out of the UK, which was the intended market, and refurbished by the curator.
,
Manual TBD

ISRM 13.01.27.27
Unisonic 767 Electronic (Slide Rule) Calculator sn179220
1974-1975 - $ ?

The 767 is a basic four function calculator with a SQRT key which qualifies as a slide rule. It is more suited for the a desktop, but that was most likely the designer's intent. Smaller calculators with the same styling, such as the Unisonic 1011, were produced at the same time as the Unisonic 767, so buyers did have a choice. Aluminum sheet metal is used to trim over the plastic with the goal of making these look classier to an executive. The 767 has a green VFD display powered by 4 C size batteries. Unisonic Products Corporation was an American manufacturer established in 1972 as a distributor of consumer electronics. Their first calculator versions were called 'SLIDE RULETTE'.


Unisonic 767 vs 1011 packaging sizes.

Manual TBD

ISRM 13.01.27.26
Unisonic 1010 Electronic (Slide Rule) Calculator sn179220
1974-1975 - $ ?

The 1011 is a basic four function calculator with a SQRT key which qualifies as a slide rule. This unit has the same styling as the Unisonic 767, but it is only half the size. Aluminum sheet metal is used to trim over the plastic with the goal of making these look classier to an executive. Both the 767 and 1011 have green VFD displays powered by 4 batteries, but the 1011 uses AAA's while the 767 uses C's. The 1011 is obviously more portable. Unisonic Products Corporation was an American manufacturer established in 1972 as a distributor of consumer electronics. Their first calculator versions were called 'SLIDE RULETTE'.

Manual TBD

Calculators Introduced in 1975

Supporting Advertisements for Prices and Dates:

Scientific Slide Rule Calculator Comparisons, Feb 1975, New Scientist Magazine

Guilford Calculator Centre Ad, Feb 1975, New Scientist Magazine

Mountaindene Ltd. Ad, Feb 1975, New Scientist Magazine

Cavendish Sales Ad, Nov 1975, New Scientist Magazine

Landau Radio Ltd. Ad, Nov 1975, New Scientist Magazine

Executive Calculators Ad, Nov 1975, New Scientist Magazine

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

ISRM 13.03.30.01
Litronix Solid State 1602 Slide Rule sn46836
1975 - ~$??

This is four-function calculator with expanded memory functions by the Litronix company and has 'SLIDE RULE' printed on the keyboard, however there are no slide rule functions. With a brown case, raised buttons keys and a large LED digits. display with digits. It takes advantage of using newer Integrated Circuits with all the processing done on one chip. A mystery calculator as identical models replace 'slide rule' with 'memory' on the faceplate. The model 1603 actually has a squared and SqR key instead of M+ and M-, so this could be a mixup in labeling at the factory. See the image of the 1603 below and the 1602 'Memory' to the right. All the keys on the later are white.
Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line).
Manual TBD


Litronix 1602 Memory Guy Ball Photo


ISRM 13.05.15.01
Litronix Solid State 1603 Slide Rule sn216455
1975 - ~$??

This is your basic slide rule calculator with square, square root, percent and memory functions by the Litronix company. It has 'SLIDE RULE' printed on the keyboard, just like the Litronix 1602 which has no slide rule functions. With a brown case, raised buttons keys and a large LED digits. display with digits. It takes advantage of using newer Integrated Circuits with all the processing done on one chip. Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line).
Manual TBD


ISRM 13.01.27.12
Enterprex SR-55 Junior Electronic Sliderule Calculator
1975 - $??.??

This is an obvious example of a calculator trying to represent itself as a slide rule!. It has 30 keys, with 1/X, X2 and SQRT slide rule functions. 2 AA batteries power a green Vacuum Florescent Display. Enterprex imported calculators from several Asian companies, most of which were from Tiawan and Hong Kong. They operated for about 7 years from 1975 through 1983, but fell victime to the lower prices of Japanese companies, along with a lawsuit from TI and HP, which did not allow them to produce scientific calculators, limiting their poential market. They then concentrated on making novelty (credit card sized) calculators for promotional purposes.
Manual TBD

ISRM 12.09.15.01
Melcor SC-645 Electronic Slide Rule Calculator sn844861
1975 - >$49.95 kit ($69.95 Assembled)

Another great example of a calculator as a 'slide rule' alternative with the picture of a Pickett 140-T on the cover of the manual. The SC-645 is basically the same as the SC-635, except for the color of the keys and the use of a slide switch instead of a rocker. The SC-645 fixed the ROM bug that caused the SC-635 to be sold at discount prices. Melcor Electronics Corporation of Farmingdale, New York (USA) was one of the first US companies to enter the pocket calculator business. Components can be swapped between the two units. The unique (and now obsolete) battery was swapped out with a removable setup of an R/C toy cable set and three 3/4size AA NiCds. (See pictures). These can be charge with a 9VDC charger using a subminiature phone jack (Like the TI AC9180 charger).
More info on Melcor

Manual (3.07Mb)

(SC-635 with SC-645 label)


ISRM 13.02.03.03
Dixon's Prinztronic SR88M sn518318
$-17-1975 - £16.95

This calculator has the minimal slide rule function of a square root key and uses a single green Vacuum Flourescent Display (VFD). It is operated by four AA batteries. It was made in Japan, possibly by TEAL (Tokyo Applications Laboratory), specifically for Dixon's, a UK electrical retailer, like Radio Shack, that rebranded many forms of calculators. It uses a Texas Instruments CPU. This specimen has a receipt for when it was purchased from Dixons in the town of Bath, England.

Manual (2.88Mb)



Dixons Receipt


Rockwell 63R Electronic Slide Rule sn259209
1975 - $99.99

There is no doubt that this was 'slide rule' calculator with the label on the front. This classic Rockwell design is a little larger than most. Odd pivoting keys in the normal Rockwell colors. It has an 8+2 digit blue VFD display with a ninth digit (and intervening one) for the minus signs. Display input starts at the left rather than the normal right. This particular specimen was used by a Hughes Aircraft employee and it had an asset tag, meaning the company owned it. It was assembled in Mexico.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

Rockwell Calculator Ad


Rockwell 63R Box End


Texas Instruments TI-2550-II Memory Calculator sn048274
October 17, 1975 - $49.95

This is the cost reduced successor of the 1974 ($99.95) TI-2550 basic calculator. It added minimal slide rule functions and the housing is identical to the SR-16 II, with a different keyplate. The TI-2550 II uses two sliding switches and a green VFD (Vaccum Fluorescent Display), a rare combination in TI's calculator history.This calculator was quickly replaced by the TI-2550 III, within 6 months, as keyboard without a [+/-] key was not too useful.

Manual (2.77Mb)


BP-2

ISRM 12.08.15.18
Hewlett-Packard HP-55 Programmable Slide Rule with timer sn1505A-05932
1975 - $395.00

Coming out a year after the HP-65, the HP-55 didn't generate quite the same level of excitement. It had no card reader and only 49 lines of program memory. (And, of course, a much lower price.) However, it did have more than twice as many storage registers (R0-R9 and R.0-R.9), more pre-programmed functions and a quartz controlled timer. The timer was first officially introduced on the HP-55 and turned the hand-held calculator into a useful test equipment like multi-meters. Timer mode was engaged by a switch (Timer/Prgm/Run). Once engaged, the timer could be started or stopped by pressing R/S, cleared by pressing CLx, and the current time could be stored in any of the 10 registers by pressing 0-9.
Donated to ISRM by the Huang Collection.
Note:one of the lower segments is missing in the display at 3.14[1]59256 (5th digit from the left.

Handbook to be scanned soon

Faber-Castell TR3
Slide Rule w/Calculator
Circa 1975 - dm218

Faber-Castell TR3 (Der erste elektronische Taschen-Rechenstab) made by one of the premier slide rule manufacturers in Germany, attached has a pocket slide rule to the back of a similarly shaped scientific calculator with slide rule functions (making the slide rule portion redundant).
Manual TBD

1975 Ad
WANTED
for Exhibit

Aristo M42 Electronic Slide Rule sn2LL13-0716
1975 - $unknown

Dennert & Pape (Aristo) was one of the world's premier suppliers of slide rules in Germany. They stopped slide rule production and created their own line of electronic slide rules. The M42 is a wider version than the previous generation of the basic slide rule with memory (see M65 in 1974) as it had to accomodate a single VFD tube from Japan (as opposed to the smaller red LEDs from Hewlett-Packard. It uses only 2 AA replaceable batteries to drive the display, as the VFDs required less voltage, as compared to the red LEDs. It has a 5x5 keyboard matrix with no function key.
Manual TBD

Aristo M66S Electronic Slide Rule snNone
1975 - $unknown

Dennert & Pape (Aristo) was one of the world's premier suppliers of slide rules in Germany. They stopped slide rule production and created their own line of electronic slide rules. The M66S is a wider version than the previous generation of the basic slide rule with memory (see M65 in 1974) as it had to accomodate a single VFD tube from Japan (as opposed to the smaller red LEDs from Hewlett-Packard. The 'S' denotes non-replaceable sealed nicads (2 AA size). It has a 5x5 keyboard matrix with 5 memory keys via the function key.
Manual TBD

Aristo M76 Electronic Slide Rule snF2LT04-0359
1975 - $unknown

Dennert & Pape (Aristo) was one of the world's premier suppliers of slide rules in Germany. They stopped slide rule production and created their own line of electronic slide rules. The M76 is a wider version than the previous generation of the scientific slide rule (see M75 in 1974) as it had to accomodate a single VFD tube from Japan (as opposed to the smaller red LEDs from Hewlett-Packard. It uses 2 AA replaceable batteries to drive the display, as the VFDs required less voltage, as compared to the red LEDs. It has a 5x4 keyboard matrix shiftable to another set of 5x4 keys via the function key. You might say this analogous to 'duplex' slide rule, which had double the functions of a one-side slide rule. This model has 3 slide switches, power, rad-deg, and alpha.
Manual TBD

ISRM 12.04.10.09
Texas Instruments SR-51 Super Slide Rule Calculator sn0065182
January 1975 - $224.95

The SR-51 Super Slide Rule Calculator now has a shift key, like the HP-45, which effectively doubles the number of keys. Statistical functions are now available. The war continues with HP as this is competing head-on with the HP-45. In 1976 the price of the SR-51-II is reduced to $79.95.
Manual TBD

Hewlett-Packard HP-35 Electronic Slide Rule V4 sn1364A-32400
February 1975 - $195.00

This is the last HP-35 model produced. Note that the function labels are on the keys rather than on the bezel.
More at MoHPC Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

ISRM 12.08.15.33
Hewlett-Packard HP-21 Electronic Slide Rule sn1506A60518
1975 - $125.00

The first of the 20 series, the HP-21 was essentially an HP-35 Electronic Slide Rule in a smaller, less expensive package. It used 2 AA cells rather than 3. Since the HP-21 had 33% more ROM than the HP-35 it had room for a few extra features, namely: Trig functions in radian mode. (The mode was selected by a slide switch.) Display formatting. (DSP # displayed # decimal places in scientific mode. DSP . # displayed # decimal places in fixed mode.) Polar/rectangular conversions. Storage arithmetic. This was implemented using special keys for M+, M-, Mx and M/. 10^x. The HP-21 also implemented other changes that appeared in post HP-35 calculators. For example, it provided y^x rather than x^y and the CLR key left the storage register intact.
Donated to ISRM by the Huang Collection..

Handbook to be scanned soon

ISRM 12.08.15.30
Hewlett-Packard HP-25 Scientific Calculator sn1603A67725
1975 - $195.00

The HP-25 started on the drawing board as a scientific (slide rule) calculator with a much larger set of functions than the HP-21. By the time it was done, it was that and it was programmable with 49 lines of memory, making it the least expensive and smallest of HP's programmable calculators. Like the HP-65, the HP-25 caused disbelief in many. It seemed much too small to do so much. Unlike previous programmables, the HP-25 had fully merged key steps... (All multi-keystroke entries like f COS and STO * 2 took a single step.) Engineering display mode was also a first on this calculator. The SST key was improved such that when it is held down, it displayed the line and line number about to be executed. When released, it executed the line and displayed the result. Like the HP-55, the HP-25 used line number addressing rather than labels. This made it very easy to move around while editing a program but inserting an instruction required either clever coding or reentering all instructions from that point onward.
Donated to ISRM by the Huang Collection..

Handbook to be scanned soon

Hewlett-Packard HP-27 Scientific/Business/Stat Calculator sn1611A009997
1976 (to 1978) - $200.00

The HP-27 is the "Do Everything" Model (Sci/Stat/Math/Bus) but no programming capability. The HP-27 came with a 230 page Owner's Handbook. From the Introduction: "At last, someone has made "a calculator for all seasons." The HP-27 solves the problems that you, the multi-dimensional professional, encounter everyday. Whether you are juggling budgets, answering a technical question, forecasting trends, checking lab results, or analyzing market data, the HP-27 solves problems fast and accurately to make your job easier." . . "At work, at home, or on the road... whether you are tackling the company's problems or your own, the HP-27 puts answers at your fingertips. Over a million HP business and scientific pocket calculators are in use throughout the world, so you're in good company with HP!"
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon

Faber-Castell TR4
Circa 1975 - DM268

Faber-Castell TR4 (Der erste Elektronische-Rechenstab) now includeds logaritmic functions and exponent capabilities, finally making the need for the slide rule (like the TR-1, TR-2, and TR-3) obsolete.
Manual TBD

1975 Ad
WANTED
for Exhibit

Unisonic 888 Slide Rulette sn027208
Circa 1975 - $unknown

A 4-function calculator that is included simply because of its model name. Unisonic Products Corporation was an American manufacturer established in 1972 as a distributor of consumer electronics. Although headquartered in New York City, Unisonic outsourced its manufacturing operations to various facilities in East Asia (especially in Hong Kong, South Korea, and Japan). Unisonic developed a variety of electronics, including calculators. Several of their first calculators had the trademark 'SLIDE RULETTE' even though they were missing the minimum requirement of a square root key. As the calculator industry became more competitive, they moved into game consoles and digital watches.
Manual TBD

Radofin Professional Slide Rule sn875-10125
Circa 1975.

This Radofin is a perfect example of a Slide Rule calculator. No risk of misinterpreting 'SR' as it is clearly spelled out. The model 875 is an arithmetic calculator with 8 digits precision and algebraic logic. It has a total of 23 keys with 9 functions, including 1/X, X2 and SQRT, The red LED display is powered by 4x AAA batteries mounted in a removable cartridge. This working example is missing the cover required to retain the cartridge and a contact terminal is missing. In the 70's Radofin Electronics Ltd. was run by directors Laurie Scott, his son Laurie Jr and brother Ken in London. They produced novelty radios before moving onto calculators in 1974. By 1976 they moved out of calculators and concentrated on TV electronic games. Most of Radofin's products were imported from Hong Kong and were sold in Europe, especially France, Germany and Italy.
Manual TBD

ISRM 12.04.10.05
Texas Instruments SR-50A Slide Rule sn829858
March 1975 - $109.50

The SR-50A Slide Rule Calculator had reduced manufacturing costs. The only other advantage compared to early SR-50 calculators is the higher calculating precision.
Donated to ISRM by Jeff Illsman, Longmont, Colorado

Manual (7.41Mb)


Texas Instruments TI-1200 4 Function Calculator with percent sn347374
March 1975 - $24.95

This became the low cost base line model that had dozens of variants with different colors and OEM distributors. It demonstrated the later design and technical engineering of the TI-30. Only the keyboard faceplates changed between models as hidden underneath were extra key switches, like a change sign and fully operational memory with 4 keys, that would get used by other calculators models, all using the same basic calculator integrated circuit (IC). The European model was the TI-1250.

Manual EU (3.5Mb)


Texas Instruments SR-51A Super Slide Rule Calculator sn089331
June 1975 - $224.95

The SR-51A was introduced shortly after the SR-51 to reduce manufacturing costs. The keyboard layout kept the same key functions, but moved them down and the colors changed from silverto gold trim. The original SR-51 became much sought after by collectors as it had a short production run.

SR-51 Manual(1.87Mb)


Texas Instruments SR-16-II Electronic Slide Rule Calculator sn195350
August 1975 - $49.95

The SR-16-II Slide Rule Calculator had a cheap appearance with the few black keys and the printed keyplate. Printed/colored keys cost more as each has to have their own inventory control. Uses 3 AA Alkaline Batteries. AC adaptor: AC9180 . The original SR-16 is more valuable and classier looking. The SR-16-II PWA is identical to the Zayre Concept III Advanced Slide Rule..

SR-16 Manual (4.21Mb)


Texas Instruments SR-52 Programmable Slide Rule Calculator sn042250
September 1975 - $395.95

the SR-52 tntroduced an integrated a card reader for magnetic strips, a huge memory (for the day) for 224 steps and the revolutionary AOS entry into a housing similar to the SR-50A calculator. The SR-52 was the thickest calculator ever at 1.8". The SR-52 was clearly placed against the Hewlett-Packard HP-65, later the HP-67 got identical memory space to the SR-52. Although the retail box has 'Slide Rule Calculator' printed on the outside, the sales literature does not reference Slide Rule any more.but stresses 'Programmable'.

Manual (25.7Mb)


Qualitron 1444
June 1975 - $24.95

Qualitron 1444 Slide Rule has an 8 digit green VFD with a ninth on the far left for negative, memory and error indication. Standard four functions with percentages, powers, square root, squares, reciprocal, register exchange and four function memory.
Manual TBD WANTED
for Exhibit

Korvettes XAM Model 889 Slide Rule Calculator sn5061756
1975 - $29.99

This basic slide rule calculator was sold by E. J. Korvette's, which was an American chain of discount department stores, founded in 1948 in New York City. It is notable as one of the first department stores to challenge the suggested retail price provisions of anti-discounting statutes. Founded by World War II veteran Eugene Ferkauf and his friend, Joe Zwillenberg, E.J. Korvette did much to define the idea of a discount department store. It displaced earlier five and dime retailers and preceded later discount stores, like Wal-Mart, and warehouse clubs such as Costco. The company failed to properly manage its business success which led to decline and its 1980 bankruptcy and closure. (citation)
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD


Commodore 725SR
1975 - $ ?

CMB Commodore issued over 120 calculators during the 1970s. They bought the semiconductor manufacture MOS and then went on to sell the Pet Computer, Commodore 64, 128 and Amiga computers through the 1980s.
More on CommodoreCalculators
Manual TBD WANTED
for Exhibit

Commodore SR4148R sn121055
1975-1977 - ~$120

The SR4148, a scientific slide rule calculator that has 78 keys, all with a single function (no shift key). was produced from 1974 chips and sold through 1977. It uses a red LED cluster and is powered by 3 AA rechargable NiCad batteries (3.6VDC), noted by the 'R' suffix in the model name. It uses AC adaptors (UK calls the 'Mains') DC640B, 707C, 708C or 709C. By 1976, the term 'slide rule' was not used in Commodore's advertising as it was in 1975, as they were now thinking ahead toward programmable computers. Even the manual that came with this specimen states: "Thank you for selecting our new scientific calculator. We prefer to call it a mini-computer because of its ability to handle so extensive a range of complex assignments across a broad spectrum of basic and advanced mathematics." The ad on the right was from an October 1976 New Scientist magazine.

Note: This calculator looks exactly the same as the 1978 SR-4120D which uses a 9V disposable battery. Disposables became more popular as Large Scale Integrated circuits advanced in technology with more of the calculator on one chip which reduced the power consumption of the calculator. This made them that much more portable and relieved the user from being near a charging source. This SR4148R needed to be taken apart and its NiCads replaced because they corroded over the last 40 years.

Manual TBD

CBM ad, Oct 1976 New Scientist

Commodore SR-9120D sn03697 (V1)
1975-1976 - ~$120

Commodore's SR-9120D advanced scientific slide rule using much of the same parts as the SR-1800, but uses a red LED display. It has a shift key for increasing the number of functions available to the user. The '12' in this silver model number denotes the number of digits displayed. The 'D' means it had disposable batteries, in this case one 9V battery. CBM or Commodore Business Machines, issued over 120 calculators during the 1970s. They bought the semiconductor manufacturer MOS to produce their own calculator chips but by 1981 they abandoned calculators in favor of personal computors like the PET Computer, Commodore 64, 128 and Amiga computers which continued through the 1980s. They were noted for putting lots of colorful buttons on their later scientific and slide rule calculators (SR prefix or suffix in the model number) while HP and TI moved toward shift keys giving individual keys multiple functions. This specimen was acquired out of Australia and was built by Commodore Japan.
Manual TBD

Commodore GL-989R Portable Electronic 'Slide Rule' Calculator
1975 - £14.00

The Commodore GL-989R Portable Electronic Calculator is an arithmetic calculator with slide rule functions (sqr root, 1/X, X squared) with memory. It has 8 digits precision and algebraic logic with a total of 8 functions, 19 keys and a VFD (vacuum fluorescent) display. The power source is Sealed battery pack with 3 nicads. It was manufactured in Japan and was part of Commodore's 'Custom Green Line' because of the green VFDs. An advertisement in the New Scientist magazine describes this calculator as "CBM 989R Slide Rule - Scientific Green Display".

Nov 1975 New Scientist
Executive Calculators Ad

ISRM13.01.27.02
Commodore SR7919 Electronic 'Slide Rule' Calculator
1975 - £12.95-15.20

The compact SR7919 was made in USA and England and is a full electronic 'Slide Rule' with the 'SR' prefix. It performs arithmetic operations with 18 keys and a shift key that adds another 18 scientific and memory functions. The display is an 8 digit red LED with bubble lens with a ninth digit for negative, function select and error indicators display. The power source is a 9V disposable battery. It came in biege or black packaging. Each button has a two color label showing operators or 2nd functions. This was a cost savings measure to utilize the molds for several models. Most calculators after this evolved with functions labels on faceplates. This calculator was advertised by several retailers in the November 1975 supplement of The New Scientist Magazine.

Donated to ISRM by Scott Reynolds of Vintage Calculators Inc


Nov 1975 New Scientist
Executive Calculators Ad


Nov 1975 New Scientist
Cavendish Sales Ad


ISRM 13.01.27.04
Compex SR-10 Slide Rule Calculator
1975 - $ ?

Compex was a brand manufactured in Tiawan and Hong Kong and imported by Cal-Comp Electronics, Inc in the USA. The Hong Kong manufacturer was Nam Tai Electronic Company in Kowloon. Compex provided 4 models of slide rule (SR prefix) calculators, the SR-8, SR-10, and later the SR-40 and SR-55. The SR-10 had the bare minimal slide rule function of a SQRT key. The SR-40 added 1/X and X^2. The SR-55 included trig functions and exponential operations. Like most of the calculators coming out of China, in 1975, the the SR-8 and SR-10 had the Commodore-ish appearance of red, white and blue keys to appeal to the American market.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

TI The Spirit Of 76
1975 - $14.88

This wonderful calculator was designed to commemorate the 200th birthday of the United States of America. Included here as it was a forerunner of calculators becoming a commodity as a promotional item. The European market received the TI-1260. Under the patriotic housing you'll find a basic TI-1200 calculator, nevertheless most collectors will pay much more for the Spirit of '76.

Manual (3.3Mb)


TEAL SR82 Scientific Memory sn510891
c1975 - $???

This scientific Slide Rule calculator was made by TEAL, Tokyo Electronic Application Laboratory Ltd. TEAL entered the calculator business in late 1968 and sold OEM products to Toshiba, Hitachi and Canon. The company was greatly affected by the calculator price war of the mid 1970s and went out of business in 1978. After that only 2 companies, Sharp and Casio, remained as an electronic calculator company in Japan.
Manual TBD

Calfax 899S sn213754
c1975 - $???

This scientific Slide Rule calculator was made in Hong Kong and distributed by Calfax Inc. (New York, USA). It uses red LEDs with a 9V battery. This specimen is innoperative. Calfax had over a 10 models and only seemed to produce calculators between 1975-1976. Another loser in the calculator wars between TI, HP, Casio and Sharp.
Manual TBD

Panasonic 8220U sn99409435
c1975 - $???

This is a minimal Slide Rule calculator with 8 functions (+,-,x,/,sqrt, pi,%,+/-) with memoty, 24 keys and a VFD (vacuum fluorescent) display. The power source is 2xAA batteries. Panasonic is a division of Matsushita Electric Corporation. This is a nice compact version, and they produced over 250 calculator models from 1970 through 1986. Yet, they did not gain as mich of a foothold in the slide rule/scientific community, as the other other Japanese rivals, Casio and Sharp, and the dominant US makers, TI and HP.
Manual TBD

ISRM 12.09.26.02
Montgomery Ward P202 Memory+Electronic Calculator, sn57X-11899
1975 - ~$50.00

The P202, model number DAN-8656A, upstaged the P200 (A rebranded TI-2550) and included more slide rule functions, which was a capability referenced on the 2nd page of the manual. The manual also has a note from its owner that it was purchased March 25, 1975. It has 20 keys with 8 additional functions. Although assembled in the U.S.A. it used Japanese components like the blue VFD driven by a 9V battery.
APF, Lloyd's or Novus, along with TI, were OEM manufacturers of Montgomery Ward calculators. Montgomery Ward closed its business in December 2000.

Manual (1.98Mb)


Page 2 mentions "slide rule"

ISRM 12.09.26.04
Unisonic 1548 Slide Rule Calculator sn065283
1975 - $??.??

The Unisonic 1548, claiming to be a "Technological Miracal!!" on its box cover, is an arithmetic calculator with slide rule functions. 8 digits precision is displayed using red LEDs and uses algebraic logic. It has 13 functions, 30 keys. The power source is 2 AA batteries. This unit was manufactured in Hong Kong.

Manual (714Kb)


ISRM 12.09.26.03
Unitrex Mini Handy 80SR snA57K83011
1975 - $??.??

Unitrex was a brand of calculators distributed by Unitrex of America in New York, which later moved to California in the mid 1970's. Calculators were made by Eiko Business Machine Co., Ltd in Japan which also OEM'd slide rule calculators to Montgomery Ward (US), Bohn, and Quelle (Germany) . The MINI HANDY 80SR is a scientific 'slide rule' calculator with 8 digits precision and algebraic logic. It has 20 functions, 26 keys and an LED display. The LEDs are very small to see, even with little magnifying lens above each 7-segment display. The power source is 3xAA batteries.

Manual (1.6Mb)


Calculators Introduced in 1976

Supporting Advertisements for Prices and Dates:

Commodore CBM Scientifics Oct1976, New Scientist Magazine

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

ISRM 13.01.27.09
Binatone Junior Slide Rule Calculator
1976 - $??.??

The Binatone Junior used a CPU by Rockwell and a single tube Futaba 9 digit VFD displaydriven by 4.5V DC, 3 x AA size batteries. The batteries were mounted in a cartridge like the TI calculators. It had the basic four functions and slide rule functions. I like this specimen with its 'slide rule' name, but I wondered if they were considering an advanced 'Senior Slide Rule' with trig functions in the future. That happened to be the Scientific Slide Rule. Both od these were made in Tiawan. Binatone Electronics Ltd. was founded in 1959 by two brothers, Gulu and Partap Lalvani, and was named after Bina, their younger sister. Out of Wembly, UK they specialised in importing consumer electronics from the far east. specialised in importing consumer electronics from the far east. With the running down of Sinclair Radionics in 1979, Binatone bought the stock and rights to the Sinclair Enterprise calculators and the Microvision televisions.

Ebay Photo

REF Need Specimen
Binatone Scientific Slide Rule Calculator
1976 - $??.??

The Binatone Scientific used a CPU by Rockwell and a single tube Futaba 9 digit VFD displaydriven by 4.5V DC, 3 x AA size batteries. The batteries were mounted in a cartridge like the TI calculators. It had the basic four functions and slide rule functions. including trig, Made in Tiawan. Binatone Electronics Ltd. was founded in 1959 by two brothers, Gulu and Partap Lalvani, and was named after Bina, their younger sister. Out of Wembly, UK they specialised in importing consumer electronics from the far east. specialised in importing consumer electronics from the far east. With the running down of Sinclair Radionics in 1979, Binatone bought the stock and rights to the Sinclair Enterprise calculators and the Microvision televisions.
Manual TBD Need for exhibit

ISRM 12.08.15.32
Hewlett-Packard HP-25C Scientific Calculator with Continous Memory, sn1806S21019
1976 (to 1978) - $200.00

An improved version of the HP-25 featuring continuous memory. Programs and data were retained when the calculator was turned off, because the new low power CMOS memory was powered even in the "off" state. It was even possible to change the battery pack and retain the memory because of a capacitor inside. Users expect continuous memory today but it was an impressive upgrade at the time. This was the first example of HP upgrading rather than replacing a calculator.
Donated to ISRM by the Huang Collection..

Handbook to be scanned soon

Texas Instruments Concept III Advanced Slide Rule.
1976 - $28.88

Zayre Corporation was founded in 1956 by Stanley and Sumner Feldberg in Hyannis, Massachusetts as a discount department store chain. In August 1975,Zayre launched the CONCEPT series of portable electronic calculators with the introduction of their first CONCEPT 24 and culminated in June 1976 with the introduction of the Texas Instruments CONCEPT I, CONCEPT II, and CONCEPT III calculators based on the TI-1200, TI-1250, respectfully. The SR-16 II disappeared in August 1979 with the clearance sales of the CONCEPT COMPACT calculators. Following the path of the Slide Rule (SR) calculators like the wonderful SR-16, the CONCEPT III was called Advanced Slide Rule. The printed circuit board (PCB) is identical to a SR-16 II. and is based on a TMS1016 single-chip calculator circuit, a member of the famous TMS1000 Microcomputer family developed in 1974. See Zayre CONCEPT Calculator Series
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD


June 24, 1976 Ad

Sep 12, 1976 Ad



Concept III vs TI SR-16-II (Datamath.org photo)

ISRM 12.08.09.01
OMRON 88SR Slide Rule sn0062097
1975 - ¥15,800

OMRON Calculators were made in Japan by Tateisi Electronics Co., Kyoto. founded in 1933 by Kazuma Tateisi and distributed in the UK, Germany and the United States through department stores like Macy's. Of the 33 known models, only 6 had the 'SR' suffix denoting 'Slide Rule'. As a scientific calculator with 8 digits precision and algebraic logic, It has 16 functions, 35 keys, 3 switches and a VFD (vacuum fluorescent) display. The power source is 2xAA batteries. OMRON was named for the district "Omuro" which was originally another name for Kyoto's Ninna-ji Temple, which is renowned for the exquisite cherry blossoms that bloom in spring.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

Dixon's Prinztronic SR99M sn272408
1976 - $?.??

This calculator has the minimal slide rule function of a square root key and uses a single green Vacuum Flourescent Display (VFD). It is operated by two AA batteries. It was made in Japan, possibly by TEAL (Tokyo Applications Laboratory), specifically for Dixon's, a UK electrical retailer, like Radio Shack, that rebranded many forms of calculators. It uses a Texas Instruments CPU. It is very similar to the Nestler OH 2001A, distributed by the German company Nestler, which was a major slide rule manufacturer.
Manual (TBD)

ISRM 13.01.27.20
Privileg SR53 Electronic Slide Rule, sn015489
1975 - $?

Quelle AG was a leading department store chain in Germany and Austria and sold most of the electronic products under the "privileg" brand. It is possible that these were manufactured by Commodore for the German market. Quelle is reported to work out deals for calculators from Texas Instruments. This very rare SR 53 is the algebraic twin (with = key like TI calc- ulators) of the privileg SR 54NC, an RPN slide rule calculator like the first HP calculators. It is a true scientific slide rule with the SR prefix in the model number. It has 8 digits precision and algebraic logic with 28 functions, 37 keys and an Red Light Emitting Diode display powered by 3x 1.5V AA Alkaline disposable batteries. The SR54NC uses 3x 1.2V rechargeable Ni-Cads. Quelle Gmbh was liquidated in 2009 and the rights to the "privileg" brand name was acquired by Whirlpool.
Manual TBD

ISRM 13.01.27.21
Privileg SR54-NC RPN Electronic Slide Rule, sn41348
1975 - $?

Quelle AG was a leading department store chain in Germany and Austria and sold most of the electronic products under the "privileg" brand. It is possible that these were manufactured by Commodore for the German market. Quelle is reported to work out deals for calculators from Texas Instruments. This very rare SR 53 is the algebraic twin (with [=] key like TI calc- ulators) of the privileg SR 54NC, an RPN slide rule calculator like the first HP calculators. It is a true scientific slide rule with the SR prefix in the model number. It has 8 digits precision and algebraic logic with 28 functions, 37 keys and an Red Light Emitting Diode display powered by 3x 1.2V rechargeable Ni-Cads, as noted by the "NC" suffix in the model name. The SR53 uses 3x 1.5V AA Alkaline disposable batteries Quelle Gmbh was liquidated in 2009 and the rights to the "privileg" brand name was acquired by Whirlpool.
Manual TBD

Texas Instruments TI-1220 True Value Hardware snA130186
April 1976 - $9.95

The TI-1220 was a TI-1200 produced exclusively for the True Value Hardware store chain. Its now the cheapest calculator out there, viewed by thousands of shoppers, just ripe for an impulse buy.

US Manual (2.2Mb)


EU Manual (3.39Mb)


Texas Instruments TI 1270 Electronic Calculator with Memory sn0251139
April 1976 - $18.95

The colorful TI-1270 was introduced as a late member into the growing TI-1200 family. At this point in the 4th generation of hand-held calculators, some say it is only a basic calculator, even though it has slide rule functions making it suitable for scientific calculations. Compare it with the SR-11, introduced only 2 years earlier as a powerful 'slide rule' calculator costing $100 more. The European model is the TI-1250.

US Manual (2.2Mb)


EU Manual (3.39Mb)


Texas Instruments SR-56 sn027562
May 1976 - $179.95

Introduced only few month after the SR-52 programmable, which had a card reader, the SR-56 was it's small brother any was 'key' programmable. The housing looked identical to the SR-51A, only the LRN-key gave you an idea of it's programmability. Compared to the SR-52 it uses only one instead of two memory-chips, reduceing the possible program length from 224 steps to 100 steps. Main disadvantage was the lack of a permanent memory storage like a card reader, but it was less than half the cost of an SR-52. The box and manual was printed with 'Slide Rule' but not the marketing literature.
Manual TBD

Texas Instruments SR-40 Electronic Slide Rule sn1243657
June 1976 - $49.95

Uses a new manufacturing approach within Texas Instruments. Everything is snapped together, no screws within the whole calculator. Comparable to the previous SR-50A and the later TI-30. This can use a standard 9V battery.
Donated to ISRM by Ted Hume, San Angelo, Texas

Manual (5.05Mb)


ISRM 12.04.10.01
Texas Instruments TI Business Analyst sn7753056
June 1976 - $49.95

The Business Analyst was the first in a successful line targeting financial calculations. It continued with the facelifted Business Analyst I, the LCD model Business Analyst II and you'll find in each scientific/programmable epoch a financial variant. Along with many 'slide rule' functions the BA was able to perform 5 different calculation modes: Standard math, Annuities, Compound interest, Profit margin, Linear regression. No mention of slide rule in literature but there were plenty of slipsticks that could do these calculations as well.
Donated to ISRM by the Huang Collection.

Manual (5.6Mb)


Leaflet (1.9Mb)


Texas Instruments SR-56P
Late 1976 - $139.95

SR-56P Programmable had lower price from the SR-56 and the word 'Programmable' located under the model number.
Manual TBD WANTED
for Exhibit

Texas Instruments SR-51-II advanced slide rule calculator sn6558606
June 1976 - $224.95

The advanced slide rule calculator is a very interesting hybrid. It used the packaging of the SR-51A and the advanced chip of the future TI-55. This is the last TI calculator to use the 'SR' prefix in its model number.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP. so an image was used from another. A donation of a working replacement would be appreciated.

Manual (10.9Mb)


ISRM13.01.27.11
Commodore SR-5190R Scientific/Stat Slide Rule sn005434
1976 - $?

Commodore Business Machines, founded in 1955, was one of the more popular brands of calculators produced in the 1970's. They relied on chips from Texas Instruments until TI jumped into the calculator business. The complex SR5190R was made in England is a full electronic 'Slide Rule' with the 'SR' prefix. The 'R' suffix denotes 'rechargable'. The 5190 represented the number of keys and functions, although there are 49 keys, with another 42 functions, 91 total, plus a power switch. It performs arithmetic and scientific operations, with memory, and also metric conversions and statistical functions. A slide rule aficianado would have loved this one as it took the place of 3 slipsticks! It has a 14 digit red LED (11 mantissa + 2 exponents and a deg/Rad indicator). The label on the back reccommends using AC adaptor no. DC.640 or 707 or 708 or 709, which provide 6V at 300ma. This unit came from Greece (with no batteries should have 3 1.2V AA NiCads) but with a 220VAC adaptor 6VDC output. It tested OK when jumpered with 6V.
Manual TBD

Commodore SR-1800 Electronic Slide Rule Calculator sn80383
1976 - $?

Commodore's advanced scientific slide rule models include the SR-1800, which has a green fluorescent display and a stylized wedge-shaped case. It has a shift key for increasing the number of functions available to the user.
Manual TBD

Commodore 9R25 Portable Mini Computer sn17034
1976 - $??.??

The 9R25 Portable Mini Computer, assembled in England with Japanese components, has the basic slide rule functions but not much else. Its claim to be a 'Mini-Computer' was a bit exaggerated, especially since there was no programming capability, but it does give us foresight into where Commodore Business Machines was heading.

Manual (5.07Mb)



ISRM 13.01.27.14
Commodore GL-997R Portable Electronic Memory Calculator
1976 - $??.??

The Commodore GL-997R Portable Electronic Calculator is an arithmetic calculator with memory functions and percent key. It has 8 digits precision and algebraic logic with 23 keys and a VFD (vacuum fluorescent) display. The power source is rated at 4.5V in a sealed battery pack with 2 nicads. The recommended adapter is the CBM DC-420B. It was manufactured in Japan and was part of Commodore's 'Custom Green Line' because of the green VFDs.

Privileg SR58D-NC Electronic Slide Rule, sn42902
1976 - $?

The Privileg SR58D-NC Elektronik-Rechner (aufladbar) is an electronic slide rule with 8 digits precision and algebraic logic. It has 25 scientific functions, 35 keys and a VFD (vacuum fluorescent) display. The power source is 3x 1.2V AA rechargeble Ni-Cad batteries ("NC" suffix in model number). It is possible that these were manufactured by Commodore for the German market and distributed by Quelle International, a German chain store. Quelle is reported to work out deals for calculators from Texas Instruments.
Manual TBD

Soviet (Russian) Elektronika sn078092
1976 - $??

The non-USA companies were slow on the catching up, but by 1976 there were scientific calculators popping up out of Russia, Japan and Germany. This is one of the first to come out of the Soviet bloc. It came with a 220VAC adaptor. They use button /disc/can/lozenge/land-mine shaped batteries, 33mm dia x 9mm thick, that they call D-0.55C (B3-18A, B3-19M, B3-21, B3-34 calculators).

Manual TBD

Soviet (Russian) Elektronika
1976 - $??

Another version of the Soviet Slide Rule Calculator. This is a typical example of the Soviet GOST standards to be followed amongst different factories (Leningrad, Unkraine, Romania) to be identical but with with minor variations in implementations and design.
Manual TBD WANTED
for Exhibit

Texas Instruments TI-2550-III Memory Calculator sn253073 MTA4677
1976 - $24.95 (£24.95)

This version replaced the TI-2550-II in a few months to add the [+/-] key, but eliminated the [F/2] decimal point switch. Both used a blue VFD (Vacuum Fluorescent Display) which, prior to these TI models, were only used in Japanese made calculators. Cost optimized, this calculator used one AA NiCd in the BP-3 battery pack, since then VFD required less voltage than the TI Red LEDs of other TI models. The operating time was very short.
Donated to ISRM By the Huang Collection

Manual (2.75MB)


BP-3


Texas Instruments TI-30 Scientific (Electronic Slide Rule) sn244096
June 13, 1976 - $24.95

This is the defining moment of the death of the slide rule. When the TI-30 was released it was the same price as a high-end advanced slide rule like the K&E 4181-3, (the slide rule only has a total of 11 unique parts so this was amazing). Inside the TI-30 is identically to the SR-40, the massive cost reduction was the sum of two details: The rechargable battery pack was replaced by a simple 9V cell and the molded lettering of the coloured keys replaced by a printed key plate. Battery consumption of the TI-30 was horrible. Probably the best selling calculator ever with about 15,000,000 manufactured units between 1976 and 1983.'SR' prefix dropped in favor of 'TI'. This is one of the last TI calculators that mentions 'SLIDE RULE' in its literature. "..the powerful 48-function TI-30 slide rule calculator.". In 1980, Texas Instruments converted the TI-30 to use an LCD display, and the TI-30 II a year later in the U.S. The calculator itself remained functionally similar over the years, with solar power coming in 1982. The TI-30X IIS 2-Line Scientific Calculator is currently issued to incoming freshmen at the US Air Force Academy and is nicknamed the "Honorator" as its lack of programmability does not allow the storage of answers in memory.
Original owner: Nick Ingala (Scratched on back in two places)
Donated to ISRM by Ted Hume, San Angelo, Texas
Wanted: TI-30 with date code of ATA 2476

Manual (4.04MB)


ISRM 12.04.10.11
Hewlett Packard HP-67 Programmable sn1612S03885 (1976, week 12, Singapore)
Jan 7, 1976 - $450

This was HP's last Classic model and is the most powerful hand held calculator model that HP produced. It used magnetic cards as non-volatile storage for programs. HP code name was 'Hawkeye and uses the same Classic battery packs and chargers as the HP 35,45, 55 and 65. An HP Catalog described them as "A major leap forward in fully-programmable personal calculators". The HP-67 packed so many functions on to a small keyboard that three (orange [f], blue [g] and black [h])shift keys were needed. It has a 13 digit with plus sign 7 segment red LED display and 26 volatile memories. Its programmable with 224 steps, fully merged, labels A-E, a-e and 0-9, program editing. Benchmarks showed that it was slower than the HP-65 but that is normal when you take the same CPU technology and load it up with more applications. Yet another candidate for "best calculator ever". The magnetic card reader gives access to numberless software libraries; This particular specimen was acquired out of Salisbury, Wiltshire, United Kingdom and owned by Michael Barnes, assumed to be an aerospace engineer whose company provided this to him when it was still relevant technology. From the labels there are references to Folland (aircraft) Gun and Ejection Seat calculations, but the Folland was made over a decade before the HP67 but was bought by BAE who built components of the Harrier VTOL Jet. The Folland designs may have been used in newer aircraft. There is 4 albums of mag cards with this unit. Along with the Standard Pac (15 mag + cleaning card) and M.E. Pac I (26 Mag cards), The owner programmed 73 additional mag cards relating to his work. There were 30 cards left blank in his albums. Obtained with the assistance of Rod Lovette, UK

Handbook to be scanned soon


REF
Omron 12SR RPN Scientific Calculator
1976

This Scientific Calculator 12SR, with the 'slide rule' suffix, was manufactured by OMRON Tateisi Electronics of Japan. OMRON calculators are a class by itself and built like a tank. The keyboard, the housing, even the battery compartment are from a different quality than your average calculator from the 70s. Mostek, the chip maker of the original Hewlett Packard HP 35 and dozens of other early HP calculators, introduced in 1975 a sensational set of Integrated Circuits with the MK50075A "Data Processor" and two sets of ROM's with 1k*15bits, each, defining the algorithm of the product: MK50101/MK50102: Financial calculator and MK50103/MK50104: Scientific calculator We know only six calculators based on the MK50075A and MK50103/104 chip-set: APF Mark 55, Corvus Model 500 and its twin Emerson E12, this Omron 12SR, the Sanyo CZ-2901 and Privileg SR54NC.But they all have two things in common: RPN and superior performance.s. Image and text Courtesy of Joerg Woerner
Manual TBD



Calculators Introduced in 1977 - The Transition Year

Supporting Advertisements for Prices and Dates:

Commodore Pre-Programmables early 1977

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

ISRM 13.02.02.01
Commodore SR-9190R Electronic Slide Rule Calculator sn144629
1977 - $48.88

Made in England based on Commodore's MOS chip designs. This 49 key Scientific Slide Rule, has over 117 directly accesible functions with a 14 digit red LED display powered by 3x N450AF rechargable NiCad batteries (Adapter DC-505, 707, 708 or 709). This model was late in the game and was one of the last models produced before Commodore abandoned calculators for Personal Computers. The keyboard has grey-scale keys which is a departure from their red-white-blue of the past, which were copied by many Hong Kong manufacturers. This calculator had a lot of bang for the buck.

Manual (500Kb)


Popular Science Nov 1977

ISRM 12.08.15.32
Hewlett-Packard HP-29C Programmable Scientific Calculator with Continous Memory, sn1806S20184
1977 (to 1979) - $195.00

The HP-29C was the top high-end model and last of the 20 series calculator. It had 98 program steps with fully merged keycodes and 30 storage registers. 16 were directly or indirectly addressable and the rest were only indirectly addressable. The recently developed continuous memory allowed information to be kept intact even when the calculators were off. The entire program space, and the X register were continuous, but the rest of the stack was volatile. Memory registers were split. The 16 directly addressable registers were continuous whereas the other 14 indirectly addressable registers were volatile.
Donated to ISRM by the Huang Collection..

Handbook to be scanned soon

ISRM 13.01.27.22
Silver-Reed 80 Electronic Calculator sn80985517
1977 - $unknown

Silver Reed Ltd. began operations as Marukoshi Knitting Machines Ltd. in Tokyo in the 1950s and in 1967 the company name was changed to Silver Seiko Ltd. It claims to be the first company to sell electronic home knitting machines as early as 1977, and, as as their technology, began selling rebranded calculators and electric typewriters. The 80 has the basic slide rule functions of 1/X, X^2, SQRT, % and Pi keys. the 1st version of the SR80's did not have any, the 2nd version had just a SQRT key. This was made at the time when calculators were getting away from identifying themselves with slide rules, so it it interesting that the 'SR' prefix was dropped, even though it had more slide rule functions than the SR80. Maybe SR was not there as the company initials? This calculator uses only 1 AA battery driving the green VFD display as IC's were getting less power hungry.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD


ISRM 12.08.21.00


Texas Instruments TI-55 Advanced Slide Rule Calculator with Statistical Functions and Progammability, sn2373004
1977 - $??.??

On the cover ofthe brochure: "Advanced Slide Rule Calculator with Statistical Functions and Progammability". 'SR' prefix dropped in favor of 'TI'. This was a great calculator for mechanical designers and engineers as it included metric conversions. From a technical aspect the TI-55 continued the ideas of the SR-40 with three main differences: The LED-stick using LED chips mounted and bonded to the printed circuit board, was expanded to 12-digits instead of the 9-digits. The ON/OFF key was replaced by a mechanical slider and the battery connector was changed from a 9V battey style to a small 3-pin header connected to a BP-7 battery pack which had a single 1.2V NiCd in it. A capacitor circuit is charged to bring the voltage up to 9V. Although the usage of cheap 9V batteries wasn't possible, it is an easy conversion to re-wire these. More at datamath
Donated to ISRM by the Huang Collection.

Manual (10.5MB)


Brochure (2MB)


ISRM 12.08.16.17
Texas Instruments TI Programmable 57 sn6749896 LTA4677
May 1977 - $79.95

Programmable 57 Slide Rule Calculator.. 'SR' prefix dropped in favor of 'TI'. Introduced together with the TI-58 and TI-59 the TI-57 represented the low budget programmable calculator of that epoch and replaced the SR-56. Unbelievable that this powerful calculator made use of the one-chip approach of the SR-40 calculator. This is the last TI calculator that mentions 'SLIDE RULE' in its literature. The TI-58 and TI-59 literature does not, they compare themselves with computers, instead. By October 1981 the price on this was $39.95.
Donated to ISRM by the Huang Collection.
Manual TBD

ISRM 12.08.16.38
Texas Instruments TI Programmable 58 sn3757137 LTA4877
May 24, 1977 - $124.95

Programmable 58 Slide Rule Calculator. 'SR' prefix dropped in favor of 'TI'. Introduced together with the TI-58 these calculators introduced the Solid State Software Modules, with up to 5000 program steps. On the backside of the TI-58/59 is a small lid with a place for a drop-in module. The Master Library with 25 different programs was included and more modules directed at specific disiplines and operations were also available. Compared with the SR-56 the memory space was raised by a factor of four, sporting up to 60 memories or 480 program steps. A new flexible aproach allowed the conversion of 1 memory to 8 program steps, base configuration was 30 memories and 240 program steps.
Donated to ISRM by the Huang Collection.
Note: This particular specimen had broken battery contacts and was repaired by soldering a set of connector cables to a rebuilt battery pack with 3 new NiCds. See photo on right.

Workbook (20.9MBkb)


Brochure (4.1MBkb)


ISRM 12.04.10.08
Texas Instruments TI Programmable 59 sn9437640
May 24, 1977 - $299.95

Programmable 59 Slide Rule Calculator.. 'SR' prefix dropped in favor of 'TI'. Introduced together with the TI-58 these calculators introduced the Solid State Software Modules, with up to 5000 program steps. On the backside of the TI-58/59 is a small lid with a place for a drop-in module. The Master Library with 25 different programs was included and more modules directed at specific disiplines and operations were also available. An even greater program collection for the TI-59 resulted from the Professional Program Exchange (PPX-59) initiative started in November 1977. By November 1981 the price was reduced to $180.00.
Donated to ISRM by Jeff Illsman, Longmont, Colorado

Workbook (20.9MBkb)


Brochure (4.1MBkb)


Texas Instruments TI-1025 snNone
June 1977 - $11.77

Introduced together with the TI-1000 this one uses a (Japanese) green vacuum fluorescent display a departure from TI's red LEDs. The calculators were manufactured either in El Salvador, Hong Kong, Spain or USA. Calculators with different nameplates were sold from Western Auto as Citation and the Dutch department store HEMA.

Manual (949Kb)


Nestler OH1002A slide rule calculator snNone
1977 - $unknown

The German company Albert Nestler KG was one of world's most respected slide rule makers, and the favored choice of many rocket scientists like Wernher von Braun and Sergei Korolyov as well as Albert Einstein, This basic slide rule calculator, with a square root key, was Nestler's attempt to move into the electronic slide rule market. The Nestler family was caught by surprise when calculators emerged on the scene, and they were unable to adapt to save the company when their products and manufacturing equipment became obsolete by 1977. They went to Japan (possibly to Tokyo Applications Laboratory) to create a line of calculators, but having to rely on outside semiconductor technology they were unable to create a sufficient market share to maintain their factories. Consequently they had to lay off their entire German workforce. This unit uses two AA batteries driving a green VFD display.
Juergen Nestler, the great grandson of the founder Albert Nestler, is a generous contributor and friend to ISRM.
Manual TBD

ISRM 12.08.09.03
Nestler T52 slide rule calculator sn102280
1977 - $unknown

The German company Albert Nestler KG was one of world's most respected slide rule makers, and the favored choice of many rocket scientists like Wernher von Braun and Sergei Korolyov as well as Albert Einstein, This basic slide rule calculator, with a square root key, was Nestler's attempt to move into the electronic slide rule market. The Nestler family was caught by surprise when calculators emerged on the scene, and they were unable to adapt to save the company when their products and manufacturing equipment became obsolete by 1977. They went to Japan (possibly to Tokyo Applications Laboratory) to create a line of calculators, but having to rely on outside semiconductor technology they were unable to create a sufficient market share to maintain their factories. Consequently they had to lay off their entire German workforce. This unit is similar to the earlier Nestler model OH1002A but with different packaging. It also uses two AA batteries driving a green VFD display.
Juergen Nestler, the great grandson of the founder Albert Nestler, is a generous contributor and friend to ISRM.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

ISRM 12.08.09.02
OMRON 8SR Slide Rule snH0701485
1977 - $29.10 (¥7800)

OMRON Calculators were made in Japan by Tateisi Electronics Co., Kyoto. founded in 1933 by Kazuma Tateisi and distributed in the UK, Germany and the United States through department stores like Macy's. Of the 33 known models, only 6 had the 'SR' suffix denoting 'Slide Rule'. This one is a cost reduced version of the 1975 modell 88SR, using less power as well. As a scientific calculator with 8 digits precision and algebraic logic, It has 21 functions, 20 keys and a VFD (vacuum fluorescent) display. The power source is 2xAA batteries. OMRON was named for the district "Omuro" which was originally another name for Kyoto's Ninna-ji Temple, which is renown for the exquisite cherry blossoms.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc

Brochure (1.2Mb)



Brother 512SR Slide Rule snB6008511
Circa 1977 - $unknown

This 40 key scientific slide rule calculator was made in Japan by Brother Industries, Ltd., of Nagoya, Japan, using NEC chips. Brother is better known for its later daisy wheel electronic typewriters, sewing and facsimile machines. It began selling products into the US in 1954. This model uses four AA batteries and the display is an 8-1/2 digit blue VFD (Vacuum Flourescent Display) plus 2 -1/2 digits for scientific notation and minus sign. It has "sin, cos, tan, sinh, cosh, tanh, asin, acos, atan, asinh, acosh, atanh, , EXP, ln, log, e^x, 10^x, y^x, 1/x, Pi, Sqrt, x^2, +,-, x<>y, CM, RM, ME" keys
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

ISRM 12.06.23.03
Radio Shack EC-420 Slide Rule Calculator sn0034958
Early 1977 - $19.95

The Radio Shack (Tandy Corp) EC-420 is advertised as a Slide Rule Calculator with Pi Key. It first appeared in the 1978 catalog with cat #65-636, which was mailed out late 1977, and then repackaged along with the EC-421, where it was given cat #65-636A. See the catalog page. This one is made in Taiwan.
Manual TBD

Radio Shack EC-421 Slide Rule Calculator sn003662
September 30, 1977 - $19.95

The Radio Shack (Tandy Corp) EC-421 is advertised as a Slide Rule Calculator with four-key memory. It appeared in the 1978 catalog with cat #65-642, which was mailed out late 1977. This one is made in Taiwan.
Manual TBD

Radio Shack EC-495 Scientific Slide Rule Calculator sn003662
September 30, 1977 - $39.95

The Radio Shack (Tandy Corp) EC-495 is advertised as a Scientific Calculator with five memories plus statistics and math. It was alongside other calculators called 'slide rule' but this one had more advanced functions. This was available in 1977 It appeared in the 1978 catalog with cat #65-642, which was mailed out late 1977. This one is made in Taiwan.
Manual TBD


Perfect 100SR Slide Rule Calculator sn142882
1977 - $5.99

This generic (basic) slide rule calculator was produced by the OEM (Original Equipment Manufacturer) Futaba (printed on the chip) in Hong Kong and the package design was sold under various brands. This one was distributed in Germany as evident by the "2x1.5V Mignonzellen" in the battery compartment. It has the basic slide rule functions which are %, pi, 1/x and sqr root, uses two AA batteries. Unfortunately, this specimen is inoperative, and is the only one known to exist on the web.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD

Texas Instruments "The MBA" sn6887124
August 1977 - $79.95

The MBA gave you advanced financial and statistical functions and targeted the market above the Business Analyst. The brown housing gave the calculator a very exclusive note.The relation between a SR-40 and the TI-55 could easily be found with the Business Analyst and The MBA. Both the TI-55 and The MBA use a 12-digit LED-stick and a single-chip design and the mechanical ON/OFF slider. It is able to learn repetitive keystrokes. By October 1981 the price on this was $60.00.
Donated to ISRM by Jeff Illsman, Longmont, Colorado

Manual (2.7Mb)


Leaflet (2.1Mb)


Texas Instruments TI Programmer sn3719449
August 1977 - $42.50

This calculator is dated from 1979 and was popular with computer programmers to convert Decimal, Hexadecimal Octal numbering systems. A merging of technologies from slide rules to personal computers. From the Introduction in the Owner's Manual: Your Calculator is designed to perform fast accurate calculations in base 16 (hexadecimal), base 10 (decimal) and base 8 (octal) number systems and to provide conversions from one base to another. Small size and simple operation with arithmetic and logical operation capability make it ideally suited for applications in computer programming, operations, and study, including minicomputer and microcomputer applications.
Donated to ISRM by the Huang Collection.

Manual (2.7Mb)


Guide (2.1Mb)


Sharp ELSI Mate EL-500 sn62092590
1977 - $??.??

This Japanese calculator with full slide rule functions uses an 8 digit green VFD with a ninth digit for negative and error indicators. Standard four functions with change sign, powers, reciprocal, square root, DMS input, pi, trigs, logs and three-function memory. 6+2 scientific display mode. It uses two AA batteries. Sharp will become a major player in the calculator industry, outlasting most of it competitors, except for Casio, TI and HP.
Donated to ISRM by Scott Reynolds of Vintage Calculators Inc
Manual TBD


Dec 1977 Ottawa Citizen Ad
Sharp Elsimate EL-5804 Electronic Slide Rule sn74291520
Late 1977 - $39.95

A late arrival onto the 'Slide Rule' calculator scene was this long, narrow and thin scientific calculator that resembled the shape and feel of a conventional slipstick. A 1977 Willson ad states: An Electronic Slide-Rule That Looks Like a Slide-Rule. It is 179mm long, 46mm wide and only 7mm thick. Two of these put together were used as props for the Battlestar Galactica Original TV Series Viper pilot Hero leg computer. The prop was constructed of metal parts, a cloth strap with Velcro and two calculator keypads. Worn by Maren Jensen as "Athena". This calculator was only produced for one year.
Manual TBD
Battlestar Galactica
Hero Leg Computer

Calculators Introduced in 1978

Supporting Advertisements for Prices and Dates:

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

Texas Instruments TI-45 Electronic Slide Rule sn478125 dc 3578
June 1978 - DM115.00

This TI was manufactured in Italy and is the European Equivalent of the SR-40. Unlike the SR-40 with its red LEDs, this ujnique TI model uses a green Vacuum Fluorescent Display. It is powered by a disposable 9V battery. This generation uses a new manufacturing approach within Texas Instruments. Everything is snapped together, no screws within the whole calculator.This specimen was acquired out of Greece.


Manual (10.1Mb)


Toshiba BC-8111B Electronic Calculator snJ18752
1978 - $?

Toshiba began to get very involved in producing calculators for various OEM's including Texas Instruments, as they partnered with TI to use their CPU chips. The date on the TI IC is 1978, so the calculator may have been produced in 1979. This calculator has the basic slide rule function of a square root key but no trig capability. It does sport a Pi key. It uses a single 8+1 digit Vacuum Florescent Display tube powered by two AA batteries.
Manual TBD


Commodore SR-4120D Electronic Slide Rule Calculator sn115340
1978 - $?

Commodore's advanced scientific slide rule models include the SR-4120D, which has a 12 digit red LED module with bubble lens, 8+2 scientific notation display The keyboard has 48 multi-colored keys with uniquely assigned functions. Other models have a shift key for increasing the number of functions available to the user. This particular specimen was made in England but the components and boards were of Japanese origin. It uses a single 9V disposable battery which accounts for the 'D' in the model name.

Note: This calculator looks exactly the same as the 1975 SR-4148R which uses 3 AA NiCad rechargable batteries. Disposables became more popular as Large Scale Integrated circuits advanced in technology with more of the calculator on one chip which reduced the power consumption of the calculator. This made them that much more portable and relieved the user from being near a charging source. The SR4148R needed to be taken apart and its NiCads replaced because they corroded over the last 40 years. The SR4120D was very easy to change its battery.

Manual TBD

Commodore SR-4912 Electronic Slide Rule Calculator sn70369
Late 1978 - $?

Made in Hong Kong based on Commodore's MOS chip designs, This 49 key (part of the model number) Scientific Slide Rule was late in the game and was one of the last models produced before Commodore abandoned calculators for Personal Computers. It uses red LEDs and a 9V battery, the preffered power source for late 70's calculators. The display is 12 digit (again, part of the model number) red LED module with bubble lens, 8+2 scientific notation display The keyboard has grey-scale keys which is a departure from their red-white-blue of the past.
It was obtained out of Toronto, Canada.

In 1981, Commodore would abandon the calculator business in favor of Personal Computers like the PET (Personal Electronic Transactor), the C=64, C=128 and later the Amiga.


Manual (678Kb)


ISRM 12.08.15.22
Hewlett Packard HP-31E Basic Scientific (Slide Rule) Calculator sn1850A05730
1978 - $60

The HP-31E was most basic scientific member of the 30 series. It was a replacement for the HP-21 at the remarkably low price of $60. (About one half the price of its predecessor and less than one sixth its grandfather!)
Quote From The Manual: The HP-31E is another professional-quality personal product from the Hewlett-Packard line of calculators--calculators whose durability, size and ease of operation have made them the choice for use by climbers on Mt. Everest and astronauts in outer space. Doctors, engineers, scientists, and other people who require instant answers to complex highly technical problems use Hewlett-Packard calculators. You're in good company with HP!
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

ISRM 12.08.15.23
Hewlett Packard HP-32E Basic Scientific (Slide Rule) Calculator sn1923A09802
1978 - $80

The HP-31E was most basic scientific member of the 30 series. It was a replacement for the HP-21 at the remarkably low price of $60. (About one half the price of its predecessor and less than one sixth its grandfather!)
Quote From The Manual: The HP-31E is another professional-quality personal product from the Hewlett-Packard line of calculators--calculators whose durability, size and ease of operation have made them the choice for use by climbers on Mt. Everest and astronauts in outer space. Doctors, engineers, scientists, and other people who require instant answers to complex highly technical problems use Hewlett-Packard calculators. You're in good company with HP!
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

ISRM 12.08.15.20
Hewlett Packard HP-37E Business (Slide Rule) Calculator sn2052S38325
1978 - $80

The HP-37E was the lower end business member of the 30 series. It replaced the HP-22 and like most previous business calculators, it was not programmable, relying instead on a wealth of pre-programmed functions. The feature set was very similar to the HP-22. It had a few less registers but also had few more functions like factorial and 1/x and it sold for less than half the price. Collectors will note that unlike previous lower end business calculators, this one is actually rather easy to find. This might be due to the fact that this model sold at a greater discount relative to the higher end model (the HP-38E/C), or perhaps, many business users of the time just weren't ready for a programmable calculator.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

Calculators Introduced in 1979

Supporting Advertisements for Prices and Dates:

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

ISRM 12.08.15.24
Hewlett Packard HP-33C Programmable Scientific (Slide Rule) Calculator sn2134S33908
1979 - $120

The HP-33E and HP-33C were the basic scientific programmable members of the 30 series. The "E" model had conventional memory which lost its contents when power was turned off. The "C" model provided continuous memory. These calculators had two shift keys like the HP-32E so in order to make room for the programming keys, some preprogrammed features had to be omitted including hyperbolics, percent change, most unit conversions, Q, and Q^-1. Also, because memory space was needed for programming, storage registers were limited to 8. In place of these features and storage registers they provided 49 step programming similar in style to the HP-25 (plus subroutines) at about half the price. Of course, compared to the HP-25, the HP-33E/C also included linear regression and estimate, %, and degrees/radians conversion.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

ISRM 12.08.15.21
Hewlett Packard HP-34C Advanced Programmable Scientific (Slide Rule) Calculator sn2029S32423
1979 - $150

The HP-34C was the high-end scientific programmable member of the 30 series. In addition to a full complement of scientific and math functions, it was the first to offer root finding and numerical integration. New to the HP-34C, the Solve function could find real roots for any equation which could be expressed in the form f(x) = 0. The manual contained a great deal of information on interpreting results, checking accuracy, efficient coding of the formula, as well as background information on how Solve worked.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

ISRM 12.08.15.24
Hewlett Packard HP-38C Programmable Business (Slide Rule) Calculator sn2142S30106
1979 - $150

The HP-38C and HP-38E were the high-end business members of the 30 series. The HP-38E was introduced first, followed a year later by the HP-38C which added continuous memory. The HP-38E/C were the first HP programmable business calculators. Previous high-end business models had relied on the large amount of software in ROM to handle most business problems. Thanks to the decreasing costs of ROM and RAM, the 38E/C could provide those previous built-in functions and allow user programmability at an attractive price. For about 30% less than the price of the previous generation HP-22, the HP-38E provided not only programmability but a much larger financial function set including amortization, internal rate of return, discounted cash flow analysis and net present value. While the HP-22 easily replaced the HP-70, it wasn't until the HP-38E was introduced that the HP-80 was finally discontinued.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD


ISRM 12.08.15.38
Hewlett Packard HP-41C Alphanumeric Programmable Calculator sn2043A01469
1979 - $295

From The Introduction: The HP-41C represents a totally new concept in the design of Hewlett-Packard calculators. In fact, because of the advanced capabilities of the HP-41C, it can even be called a personal computing system. The HP-41C is the first Hewlett-Packard handheld calculator offering an exciting array of alphanumeric capabilities. With so many different kinds of calculator uses and applications in the world, we at Hewlett-Packard decided we could provide a significant contribution by designing and building you a quality calculator with expandable and flexible capability. The alphanumeric HP-41C is just the calculator. The HP-41C used a low power LCD display with 7 more segments than previous calculators. This allowed a full range of alphabetic characters. The characters were not as fully formed as a dot matrix display, but they had better contrast. It had four expansion module ports at the top end which could add memory or specialized programs.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP. A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

ISRM 12.08.16.02
Texas Instruments TI Programmable 58C sn4428030 ATA2981
1979 - $90

Programmable 58C Slide Rule Calculator with constant memory with Solid State Software Modules and programmable up to 5000 steps. The main disadvantage of the earlier TI-58, released in 1977, was the non-permanant program storage which was corrected with the TI-58C. Using a low-power C-MOS memory (a Toshiba TC5047 in this machine) battery drop caused by the NiCd's itself was quicker than drop caused by the memory. The Master Library with 25 different programs was included with the calculator, and additional modules were available. The TI-58C can use the TI PC-100C Security Cradle and Printer.
Donated to ISRM by the Huang Collection.
Note: This specimen has a partially broken battery contact but still works when jumpered.

58/59 Workbook (20.9MBkb)


Brochure (2MBkb)


Texas Instruments TI Business Analyst I sn0448503
1979 - $24.95

The Business Analyst-I was introduced 1979 as a facelifted low-budget version of the Business Analyst. This is after the 1972-1977 focus of this gallery but it still used red LEDs and shows another step of cost reduction. The rechargable battery pack was replaced by a simple 9V cell and the usage of a metal key plate gave a more modern appearance. Battery consumption of the Business Analyst-I was horrible, marketing guys from TI invented the after market sales of "Rechargable Kits" RK2. They used two AA-cells and a step-up converter to generate the 9V of the calculator. The next step in cost reduction was the usage of the simple, black keys of the TI-30 and a printed key plate. By October, 1981 the price was reduced to $20.00 as the LCD version BA-II was released at $40.00.

Manual (2.7Mb)


Sharp ELSI Mate_EL-206 sn90009545
1979 - $?

This calculator with the minimal slide rule function of a sqr root key, has a yellow tinted LCD screen and is operated by a 9V Battery. The early LCD's had problems with UV light affecting the crystal and had this yellow filter to protect them. Later developments eliminated the need. Ryobi also sold this model under their label.

LCD Calculators Introduced in 1980 and later (The Modern era)

After 1980, Liquid Crystal Displays became predominant as they used very little power. Several models that began life as 'Slide Rule' Calculators retained that nomenclature in the modern era such as the SR-40-LCD, TI-30-II, and TI-55-II. Others are shown here only because the museum does not know what else to do with them.They were acquired as part of lots that contained the sought after slide rule calculators or found their way here through donations from friends of the museum.
Supporting Advertisements for Prices and Dates:

IMAGE
DESCRIPTION
LITERATURE
EXHIBIT PLACARD

ISRM 12.08.15.39
Hewlett Packard HP-41CV Alphanumeric Programmable Calculator sn2324S42918
1980 - $325

The HP-41CV was the same as the HP-41C except that it had four memory modules built in for a total of 319 registers. (With the four ports still available to add other modules.) Like the HP-41C, It had four expansion module ports at the top end which could add memory or a wide selection of specialized programs. These calculators could be attached to external HP-IL disk and tape drives as well as printers.
Donated to ISRM by the Huang Collection.
Note: This calculator in INOP.A donation of a working replacement would be appreciated.

Handbook to be scanned soon
TBD

Texas Instruments SR-40 LCD
1980 - $unknown

A Late arrival. The last TI with SR in the model name. The SR-40 resurrected with a Liquid Crystal Display (LCD). The original SR-40 (1976) had red LED's. Since 'SR' is in the model name, we list it here as one of the last TI slide rule calculators. This model was produced only in Brazil under license of TI to Indústrias Gerais da Amazonia S.A.*, and because of export limitations was not available elsewhere. It is comparable to the European TI-30 LCD, with modified shell and sleeve.
*Indústrias Gerais da Amazonia manufactured in the Manaus Free Zone different calculators like the rare SR-40 LCD under license of Texas Instruments. Due to various barriers to trade most foreign companies established in Brazil some kind of off-shore production. Already in 1957 by parliamentary initiative the "Zona France de Manaus" was created in the Municipality of Manaus, State of Amazonas: the Geographic Center of the Western Brazilian Amazon. Grounded on federal, state and municipal fiscal incentives, the project included the creation of an industrial, commercial and agricultural and cattle raising center. Today there are more than 600 industries, using competetive technology in the production of electro-electronic, computer science, professional equipment, photocopiers, telephone receivers, fax, and telecommunications used all over Brazil.(Courtesy of Joerg Woerner, Datamath Calculator Museum).
Manual TBD
WANTED
for Exhibit

ISRM 12.08.16.05
Texas Instruments TI-30-II Electronic Slide Rule Calculator
1982 - $18

This popular combination of practical scientific functions gets another new life in the packaging of the 'Slim-Line' calculators and gains a 'Constant Memory'. Values stored in registers are retained when the power is off. This is the second edition of the one released in 1981 The TI-30-II uses the electronics of the European TI-30 LCD and the two shell housing of the TI-35. It uses two LR44 batteries. Suprisingly, in 1982 and beyond, it still calls itself a 'Slide Rule' Calculator as seen on the cover of the manual.
Donated to ISRM by the Huang Collection..

Manual (6.13Mb)


Manual Cover


ISRM 13.05.05.03

Texas Instruments TI-55-II-LCD Advanced LCD Slide Rule Calculator
1981-84 - $50.00

BUT WAIT, THERE'S MORE! Just when we thought that 'Slide Rules' were totally forgotten by the calculator industry, Texas Instruments, in 1981, reminded us where it all started by added a new LCD calculator to the slimline series.

Its a TI-55 resurrected with an angled Liquid Crystal Display (LCD) and 45 keys. The original in 1976 had red LED's and 40 keys. We did not think this qualified to be in the gallery, but when the retail box was discovered, it clearly stated "advanced LCD slide rule calculator with programming and statistics". Datamath.org had a leaflet which showed the same text, but interestingly enough, the manual does not mention slide rule. We list it here as the LAST TI slide rule calculator. The TI-55-II features are 112 powerful functions for professional engineering, science, and mathematical applications. Modern, functional styling.


Leaflet (2.16Mb)


Taiwan Printed
Manual (1.4Mb)


USA Printed
Manual (2.33Mb)


ISRM 12.08.16.07
Texas Instruments TI Business Analyst II, sn1355958 ATA0582
1978 - $40.00

The Slime-Line Majestic series Texas Instruments started with the TI Business Analyst II with Constant Memory to introduce a financial counterpart to the scientific calculator. Manufacturing cost of the slimline models was inexpensive as the entire calculator uses one flexible printed circuit board (Flex-PCB) with the integrated circuit and a LCD-module. There is no soldering or screws fasteners within the calculator. As with all the Slim-Line series it uses 2 LR44 batteries.
Donated to ISRM by the Huang Collection..

Manual (5Mb)


Texas Instruments BA-II Executive Business Analyst snLTA0886
1984 - $unknown

Manual TBD Not for Exhibit

Aurora LCD-6
c1980 - $?

This calculator with the minimal slide rule function of a sqr root key, +/-, and %, has a LCD screen and is operated by a 2 AA Alkaline Batteries. The Aurora company was founded in 1975, and this particular specimen uses a SHARP CPU.
Donated to ISRM by Jeff Illsman, Longmont, Colorado
Manual TBD Not for Exhibit


ISRM 12.06.14.01
Sharp EL-8048 Sorokaru (Soroban-Calculator) sn001
January 1979 - ¥5500

Just as there was a delay in the acceptance of electronic slide rule calculators in the western world, the Japanese were reluctant to give up their Soroban's for the calculator without double-checking their answer on their Soroban Sharp's answer was the combination abucas/calculator. This early version was made in Japan. It uses a single 9V battery with Dimensions: 307 (W) x 87 (D) x 22 (H) mm. 310g. The
Manual TBD Not for Exhibit


ISRM 12.07.15.01
Sharp EL-428 Sorokaru (Soroban-Calculator) sn482
c1981 - ¥5500

Just as there was a delay in the acceptance of electronic slide rule calculators in the western world, the Japanese were reluctant to give up their Soroban's for the calculator without double-checking their answer on their Soroban. Sharp's answer was the combination abucas/calculator. This later version was made in Korea. it uses a single AA battery with Dimensions: 298 (W) x 78 (D) x 18.5 (H) mm. 251g.
Manual TBD Not for Exhibit


ISRM 13.09.18.05
Sharp EL-429 Sorokaru (Soroban-Calculator) sn44Y
c1984 - ¥

Just as there was a delay in the acceptance of electronic slide rule calculators in the western world, the Japanese were reluctant to give up their Soroban's for the calculator without double-checking their answer on their Soroban. Sharp's answer was the combination abucas/calculator. This later version was made in Korea.This one uses solar power. Size : W29.9(cm) x H 6.3(cm) x D1.35(cm)
Manual TBD Not for Exhibit

ISRM 12.04.29.01
Soviet (Russian) Elecktronika MK33 CCCP sn887296-8904 (V2)
1983-1990 - RUB 35 (roubles/rubles)

The Eastern Europe countries in the Soviet Bloc were hampered by the dictates of state- run companies that had standards that were at least 10 years behind the west. This is one that has all the slide rule and advanced scientific functions. It uses 3x D0.50 NiCd button cell batteries, 19mm dia x 7mm thick, that power an 8+1 digit red Light Emmitting Diode (LED)Display. The rest of the world, by now, were all using Liquid Crystal Displays. The earlier MK-33 has 1/x functions on the firmware and 1/x functions on the faceplate. One or two years later, another MK-33 was produced, with different firmware incorprating the square root function with a properly marked faceplate. The PCB's were interchangeable with both cases so it was possible that the 1/x key marked case produced a sqrt result in some units during a repair. New firmware also provided a few new functions: rounding after 2 digits and constant PI. You may get PI constant by pressing the memory recall button twice. Collectors might enjoy finding both of these variants. Variant description is based on input from Sergei Frolov of the Soviet Digital Electronics Museum in St.Petersburg, Russia.

Manual TBD


ISRM 13.01.27.18
Soviet (Russian) Elecktronika MK36 CCCP sn23816
1986-1989 - RUB 70 (roubles/rubles)

The Eastern Europe countries in the Soviet Bloc were hampered by the dictates of state- run companies that had standards that were at least 10 years behind the west. This is one that has all the slide rule and advanced scientific functions. It uses 3x D0.25 NiCd button cell batteries, 25mm dia x 9mm thick, that power an 8+1 digit Vacuum Fluorescent Display. The rest of the world, by now, were all using Liquid Crystal Displays. The case is made of thin aluminum sheetmetal. The MK-36 was carried into space on at least one occasion aboard the MIR space station by Cosmonaut Yuri Romanenko. He used for navigational and scientific work during his one-year flight from 1986 to 1987.
Manual TBD


MIR Cosmonaut Yuri Romanenko, 1986

Hewlet Packard HP20S
c1987 - $?


Donated to ISRM by Scott Reynolds, Hemet, CA
Manual TBD Not for Exhibit
Hewlet Packard HP32S
c1987 - $?


Donated to ISRM by Saleem Ahmed, Broomfield, CO
Manual TBD Not for Exhibit
Hewlet Packard HP32Sii
c1988 - $?


Donated to ISRM by Mike Konshak, Louisville, CO
Manual TBD Not for Exhibit

ISRM Slide Rule Calculator Exhibit Placards (8x10)


WANTED! - Other Potential Slide Rule Calculators
Not shown in Gallery - Donations with biographies of donors (if specimen was a personal calculator) are requested

Note: with SR- or -SR, -ESR or reference in literature to slide rules. Items added to List as discovered.

Calculators in the
ISRM archives

We are trying to obtain all the physical specimens, as shown above, for the permanant ISRM - archives and to be used for public exhibits. If you can help by providing your personal SR calculator it would be appreciated by all who will view it.

50 years of working (1960-2010), Here's all the
math instruments the curator used in his career

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