The calculator provides a prime example of the technological changes that took place throughout the 1960s. At the beginning of that decade only mechanical and electromechanical calculators were available, but by the beginning of the 1970s electronic calculators reigned supreme and almost none of their mechanical and electromechanical ancestors remained in production …

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Electronic Desktop Calculators (Vacuum Tube-based)
Incorporated in 1878, the Bell Punch Company of Uxbridge, England, originally used to manufacture ticket punches for use on trams. They diversified over time, and in 1956 they started a project to produce a commercial electronic desktop calculator codenamed the ANITA.

The result was the world’s first electronic desktop computer, which was released in 1961 under the name Anita Mk 8 in England and Anita Mk VII in continental Europe. These machines were based on approximately 170 cold cathode vacuum tubes coupled with a "Dekatron" decade counter tube and "Numicator" display/indicator tubes.

ANITA

Interestingly enough, the name ANITA was intended only for internal use during the development of the device. However, this moniker was so ingrained with everyone by the time the calculator was ready for production that the company decided to stick with it. This posed a new problem, because people started to ask what ANITA stood for. Eventually, the company started to say that it was an acronym for "A New Inspiration To Accounting" (or sometimes "A New Inspiration To Arithmetic").




 
Electronic Desktop Calculators (Transistor-based)
There are a number of contenders for the title of “first commercial all-transistor desktop calculator.” These include the Friden EC-130 from the USA, the Sharp Compet CS10A from Japan, and the IME 84 from Italy, all of which were presented to the market in 1964.

Friden

Each of these devices brought something interesting to the table. For example, the IME 84 used a magnetic core memory to store the contents of its registers, while the Friden EC-130 (and later the EC-132 – as shown in the photo above – which was introduced in 1965 and included the square-root function) used a small cathode ray tube to display four lines of numbers reflecting the contents of its 4-register stack.




 
Electronic Desktop Calculators (IC-based)
As usual, there are a number of contenders for the title of “first IC-based desktop calculator.” Do we consider experimental prototypes, for example, or should we restrict ourselves only to commercially released devices? In the case of the latter, a good example of the ilk would be the Sharp Compet 22, which was presented to the market in 1968.

Sharp Compet 22

As shown above, this particular device displayed results to 14 digits of accuracy using Nixie tubes. One interesting aspect of this model is the knob located to the upper-left of the keyboard, which was used to set the position of the decimal point.




 
Electronic Handheld Calculators
The thing about electronic products is that they keep on getting smaller and faster as technology develops and it becomes possible to squeeze more transistors into an integrated circuit. Thus, it wasn’t long before people started to think that desktop-sized calculators were a tad on the large size and that it would be jolly handy to have something that would fit in the palm of one’s hand or – dare one say it? – in one’s pocket.

Sharp QT8-B

In 1969, Sharp introduced a small desktop calculator called the QT8-D that required only four integrated circuits. A little later, in early 1970, they replaced the AC power portion of this device with rechargeable batteries. The result was the first battery-powered "hand-held" calculator (at a sturdy 5.2 inches wide by 9.6 inches tall and 2.75 inches thick, it was way too large to fit in a pocket – unless you happened to have outrageously large pockets), which was named the Sharp QT8-B.




 
Electronic Pocket Calculators
The first experimental model of an electronic pocket calculator – known as the “Caltech” project – was created by Texas Instruments (TI) in 1966 [this machine is now preserved at the National Museum of American History (a part of the Smithsonian Institution) in Washington, DC, USA]. This was followed circa 1970 by the first commercially available unit; a portable (hand held) printing calculator called the Pocketronic. Created as a joint effort by Texas Instruments and Cannon, this four-function device could add, subtract, multiply, and divide.

Although the Pocketronic is classed as a “pocket calculator” by many, you would have required a sartorial dress sense with clothes sporting oversized pockets to accommodate its 4-inch width, 8.2-inch length, and 1.9-inch thickness.

Busicom LE-120A

In fact, the honor of the first device that could truly be called "a pocket calculator" (without laughing) goes to the Busicom LE-120A "handy" from Japan, which appeared on the scene sometime around late 1970 and early 1971. In addition to being the first true pocket calculator (it was only 2.6 inches wide by 4.9 inches tall and 0.9 inches in thickness), this little rascal also holds the honor of being the first calculator to display values using a light-emitting diode (LED) display and the first hand-held calculator to feature a single “calculator-on-a-chip” integrated circuit. Note that this IC, which was manufactured by M ostek, was a special-purpose, calculator-specific device; that is, this component was not a general-purpose computing engine as introduced in the Microprocessor discussions below). A little later, Busicom introduced their LE-120S model in 1971, which was a slightly cheaper version of the LE-120A.



Note: The material presented here was abstracted and condensed from The History of Calculators, Computers, and Other Stuff document provided on the CD-ROM accompanying our book How Computers Do Math (ISBN: 0471732788).