How to Collect LED Pocket Calculators

by Larry Gilbert


Brief History

Prior to 1963, all calculators were either mechanical or electro-mechanical. Pocket models consisted primarily of basic stylus-driven units which were capable of adding and subtracting only. An exception was the Curta, a beautifully-made, high-quality unit capable of all four arithmetic functions and using a complicated system of gearing to achieve its results. For more advanced calculations, one would resort to a slide rule, some of which were made in small circular and cylindrical forms or in a short pocket-sized format.

In 1963, Sumlock Comptometer (in England) produced the first all-electronic calculator, the Anita, followed in 1964 by several Japanese firms, notably Hayakawa Electric (Sharp) and Sony. These were large desktop models using hundreds of transistors. Portability became possible with the invention of the integrated circuit by Texas Instruments. As they had done 10 years earlier with transistors and the transistor radio, TI sought to develop a product that could demonstrate the capabilities of the IC and they chose the pocket calculator.

TI began development of the Caltech in 1965 and completed a prototype in 1967. Canon, impressed with this device, worked with TI to develop a marketable version (eventually introduced in 1970 as the Canon Pocketronic). These were handheld printing-only units with no display.

Meanwhile, Sharp, by now producing an extensive line of desktop models, slowly began downsizing its units. In 1969, using large-scale integration technology, Sharp produced the QT-8, weighing only 3 pounds but still operating off AC. By June 1970, Sharp had developed a battery-operated version, the QT-8B, which fit into an oversized docking-type charger. Further downscaling led by early 1971 to the EL-8, a truly portable unit featuring the QT-8 tube display.

In early 1971, several other manufacturers produced portable calculators, mostly too large for the pocket and invariably using tube displays. In September 1971, Bowmar, a manufacturer of LED displays, produced the 901B (also marketed as the Craig 4501 and Commodore C110), perhaps the first true pocket calculator, possibly the first with an LED display, and certainly the first manufactured in the U.S. It was significantly more compact than the EL-8. At the same time, Busicom produced the remarkable Handy LE120A, also featuring an LED display but also the novel feature of replaceable batteries, with everything housed in an extraordinarily slim metal case.(A side note: In the annals of computing history, Busicom is most noted for contracting in 1971 with the fledgling Intel Corporation to manufacture a microprocessor chip to be used in its desktop printing calculator, model 141-PF. This chip, the 4004, was the first of the Intel series of microprocessors leading to today's Pentium.)

Prices were high for these early models, ranging from $240 for the Bowmar to $495 for the SCM Marchant 1. These high prices meant high potential profits, and dozens of companies entered the market in the 1972-1973 period. The increased competition led to innovations in styling and functionality, but also to price reductions and cost-cutting. By the end of 1972, the Casio Mini sold for $60 and in late 1973, National Semiconductor introduced the model 600 at $29.95. The price wars escalated when the semiconductor manufacturers, in particular TI, National Semiconductor, and Rockwell, began producing their own calculators in large quantities. Increased cost-cutting meant greater use of fluorescent displays, replaceable batteries, and cheaper cases. Gone were the durable Klixon keypads developed by TI and used so extensively by Bowmar and others.

At the higher end, the competition was less severe. The Hewlett Packard 35, introduced in early 1972, virtually wiped out the slide rule industry with one fell swoop. HP continued to dominate the advanced calculator market for years, eventually receiving some tepid response from others, such as National Semiconductor and Commodore, and more formidable response from TI. But HP remained one step ahead, making powerful models, including the 65, the world's first programmable pocket calculator.

As early as 1972, some manufacturers were looking at liquid crystal displays as a way to conserve power in battery-hungry calculators. Rockwell made a series of backlit LCD calculators in the 1972-74 period under the Lloyds, Sears, and DataKing names. Sharp, always the innovator, used a novel COS (Crystal on Substrate) LCD on several models between 1973 and 1976. Although the technology was eventually abandoned, these COS LCD calculators had important stylistic characteristics which prefigured the models that exist today. The contemporary style of LCD calculator appeared in 1977, at first with yellow-tinted displays and then by 1979 or so with the standard gray display we now know. The first solar-powered calculators appeared at about the same time (1976/1977).

The reduction in battery size that LCDs allowed led to much greater miniaturization. Now calculators could be made incredibly thin. One of the more interesting models was the Casio FX-48, a full scientific unit the size of a credit card. Another breathtaking model was the Casio Micro-Mini (only 2.5 x 1.75 inches). There had been some remarkably small LED calculators too, usually employing technological innovation that reduced battery consumption; examples include the Sinclair Executive and Sovereign, the Monte Carlo and related models, and various calculator watches.

What to Collect

Obviously, what to collect is a matter of personal taste and goals, but I will present some guidelines that I have observed.

Early models: The earliest calculators (1970-1971) include the ones mentioned in the previous discussion (Sharp QT-8, Sharp EL-8, Canon Pocketronic, Bowmar 901B, Busicom Handy LE120A) plus early Sanyo models (those beginning with ICC), Dictaphone calculators (these were made by Sanyo), SCM Marchant 1, Monroe 10 (similar to the Pocketronic), the first Canon Palmtronic (LE-10), the first Toshiba (BC-0801B), Brother 408, and Commodore Minuteman 1. In addition to their historical importance, many have unique styles and most are well-constructed. It is important to note that these were quite expensive in their day and many were bought not by individuals but by organizations. Most have not survived and can be quite scarce now.

Historically important models (other than the ones listed under "Early models"): These would include the HP 35 (first scientific model), HP 80 (first business model), HP 65 (first programmable), TI 2500 Datamath (TI's first pocket model), Sharp EL-805 (first pocket model with LCD display), Lloyds Accumatic 100 (first portable with LCD display), Royal Solar 1 and Sharp EL-8026 "Sunman" (first solar models?).

Obscure brands: In the 1972-1975 period, dozens of companies produced pocket calculators but most quickly disappeared. A few, such as Bowmar, Melcor, Corvus, and KingsPoint fluorished briefly but brightly, producing quite a few interesting models before departing. Others, such as Iain Jones, Columbia Scientific, Peripheral Magnetics, RES, and Super Cal produced a small handful of models, sometimes only one or two, before fading into obscurity. In addition to the diversity they add to a collection, these brands add considerably to the thrill of the hunt that collectors enjoy.

Calculators made by companies associated with computers or other calculating devices: The most important of these is MITS, which produced the groundbreaking Altair 8800 personal computer. Prior to the Altair, MITS manufactured 8 or so calculator models, either assembled or as kits. Commodore produced 40 or more calculator models before turning to their famous PC products. Monroe, Victor, and Friden, known for mechanical and electro-mechanical adding machines, produced some pocket calculators. So did Aristo, Faber-Castell, and Dietzgen, well-known for their slide rules.

Stylish or unusual models: Certain manufacturers produced aesthetically striking or unusual designs. Almost any model from Sinclair and Summit would fit this category. Several Omrons and Panasonics would too, as well as the Olivetti Divisumma 18, and calculators by Aristo and Braun. Unusual designs would include the Calcupen, a high-quality unit resembling a pen and using novel toggle controls, the Royal Digital III, which used a stylus for keypad input, the Faber-Castell TR-3, which consisted of a calculator on one side and a slide rule on the other, the comet-shaped Kosmos Astro, and the Sinclair Wrist Calculator. These are all quite difficult to find, as most consumers acquired more ordinary models.

Advanced models: Many collectors are drawn to the more advanced models, such as scientific, financial, statistical, and programmable units. These were sold in smaller quantities than basic models, and have a nostalgic quality to the many calculator collectors who are technical professionals

Rare models: Some calculators are notoriously difficult to find and so become important to those attempting to complete collections. Examples include the HP 10, 19C, 27, 35 (original version), and 70, the TI 150, SR-16, and SR-51, and any LED calculator-watch. Some collectors like to acquire calculators marketed in other countries because of their scarcity in the collector's country.

Pocket computers: These bear some physical resemblance to the pocket calculator, but are distinguished by their QWERTY keypads, inclusion of a high-level programming language such as BASIC, and ports for peripheral such as printers and cassette recorders. Many could be expanded with memory and application modules. The first true pocket computer was the Sharp PC-1200 (also marketed as the Radio Shack PC-1), which featured a one-line yellow-screen liquid crystal display and appeared in 1980. A more advanced model, introduced in 1982, was the Sharp PC-1500 (Radio Shack PC-2). Other early models include the HP 75C and Panasonic HHC. Some calculators are closely related to these computers; these would include the HP 65 and 67 for their programming features, the HP 41C and TI 59 for their ability to use peripheral equipment and expansion modules, and the Sharp EL-5100 for stylistic characteristics.

How to Collect

Pocket electronic calculators are still easily found at flea markets, second-hand stores, and garage sales, usually at bargain prices. Collector prices are higher but still reasonable compared to more established items. HP calculators are somewhat of an exception, as there is already a rather extensive group of HP collectors. Antique stores have not "discovered" electronic calculators yet but this may change soon as articles have begun to appear in the trade press and a collector's guide will be published shortly.

Certain calculators are much easier to locate than others; a few companies quickly came to dominate the industry. Foremost is Texas Instruments; they produced 50 or more different models during the 1970s and I would estimate that at least 1/3 of all non-HP pocket calculators during that period were made by TI. Other common brands are APF, Casio, Lloyds, Rockwell, Sears, and Unisonic.

The best reference sources are The Complete Collector's Guide to Pocket Calculators by Guy Ball and Bruce Flamm, which offers a comprehensive descriptive listing (and photographs) of pre-LCD electronic units, and A Guide to HP Handheld Calculators and Computers by Wlodek Mier-Jedrzejowicz, with detailed information on all HP pocket models to the present day.

For Sinclair calculators, the book to have is Enrico Tedeschi's Sinclair Archeology. An early reference book which touches on calculators is A Collector's Guide to Personal Computers and Pocket Calculators by Thomas Haddock. The emphasis is on personal computers, however, with the few pages devoted to calculators concentrating mostly on HP and TI.

There is an organization of calculator collectors, the International Association of Calculator Collectors. This organization consists of over 300 members and publishes an informative quarterly newsletter. They can be contacted at 14561 Livingston St., Tustin, CA 92780 USA.

Copyright @1997 Larry Gilbert