Electronic Calculators—Handheld


In the course of the 1970s, handheld electronic calculators transformed the way tens of millions of people did arithmetic. Engineers abandoned slide rules, business people gave up desktop calculating machines, and shoppers replaced simple adding machines and adders. Educators asked how much students should even learn written procedures for multiplication, division, and taking square roots. Parents bought new toys that offered both instruction in arithmetic and other games for their children.

A few calculators were programmable, offering an alternative to large computers and to the microcomputers introduced in the same decade. Like microcomputers, they incorporated changes in microprocessor technology and displays. Many companies that sold calculators, such as Hewlett-Packard, Texas Instruments, Tandy Corporation, and Commodore, would also market microcomputers and digital watches, other novelties of interest at the time. Business patterns established with calculators such as design in one country, manufacture in another, distribution by third parties, rapid introduction of new models, and decreasing cost also would appear with other electronic devices.

Handheld calculators were introduced into the United States in 1970 and 1971 by the Japanese firms of Busicom (Nippon Calculating Machine Corporation) and Sharp (Hayakawa Electric) as well as the American firm of Bowmar. Chips in early Busicom calculators were made in the United States by Mostek, while those in the Bowmar and Canon were by Texas Instruments. Hewlett-Packard Corporation joined the market in early 1972 with the HP-35 scientific calculator.  It could not only add, subtract, multiply, and divide but compute trigonometric functions, logarithms, and exponents. In other words, it did the work of a slide rule and more. The calculator sold for $395. Not to be outdone, Texas Instruments introduced its first calculator, the Datamath (or TI-2500), later that year. The device carried out basic arithmetic and sold for $149.95. In 1973, TI introduced the SR-10, its answer to the HP-35. It did not give values for trigonometric functions, but cost only $150. The TI-50 (introduced in 1974 for $170) and the HP-21 (introduced in 1975 for $125) both performed the calculations possible on a slide rule for a somewhat more reasonable price.

Inexpensive Four-Function Calculators

Early handheld electronic calculators could be ordered from manufacturers or dealers. They also sold as relatively expensive goods in department stores. In the course of the 1970s, better chips made it possible to reduce the number of components required in calculators. Liquid crystal displays required significantly less power, making it possible to operate a calculator on tiny batteries – or operate on sunlight alone. Moreover, membranes replaced individual keys on some instruments. With all of these changes, cost of the devices plummeted. By 1977, a liquid crystal display calculator known as the Teal LC811 sold regularly for $24.95, with a sale price of $19.95. By 1985, the solar-powered Sharp EL-345 sold for $5.95. Both of these calculators were made in Japan. The Sharp not only carried out arithmetic and found percentages, but had a square root key. Both calculators had limited memory for results of computations.

Programmable Handheld Calculator

Desktop electronic calculators that could be programmed were available from the mid-1960s. Prominent American manufacturers included Wang Laboratories in Massachusetts and Hewlett-Packard Company in California. By 1974, Hewlett-Packard had developed a more compact programmable device, the HP-65. Advertisements dubbed it a “personal computer,” not just a calculator. The instrument sold for $795 – plus an extra sum for a special “security cradle” that allowed one to attach it to a desk.

The HP-65 was specifically designed to assist in repeated calculations required in such disciplines as science, engineering, finance, statistic, mathematics, navigation, medicine and surveying. Toward that end, it contained a small magnetic card reader and recorder. Users who had worked out a series of commands they wished to reuse could save the program to a magnetic card. A variety of prewritten programs were available for purchase.

HP also published a newsletter where owners of the calculator exchanged information about programs. One owner of a HP-65 (not the instrument in the Smithsonian collections) was programmer Barry S. Berg. Berg used programming in many aspects of his life. The programs for his HP-65 device relate to aerial navigation, he consulted them when flying an airplane. Other, less expensive, programmable calculators soon followed, first from General Instrument and Texas Instruments and then from Hewlett-Packard itself. At the same time, the diffusion of sturdy personal computers decreased demand from computer programmers for these particular handheld devices.

Educational Games

In 1971, Jerome C. Meyer and James A. Tillotson III of Sunnydale, California received a patent for a “teaching device having means producing [sic] a self-generated program.”  Here questions for drill were selected using a random signal generator. Meyer and Tillotson thought such a machine might have many uses, but specifically showed an instrument for generating simple arithmetic problems. Given a problem, a student entered the answer. The machine checked its accuracy, with a correct answer generating a new problem. Ideas in this patent were reflected in an electronic teaching machine for drilling children in basic arithmetic called the Digitor, a device introduced by the California firm of Centurion Industries in 1974. The Digitor was a desktop, not a handheld, device. It sold to schools, not individuals.

Educational electronic games in the form of handheld electronic calculators, designed for home use, soon followed. For example, the Novus (also National Semiconductor) Quiz Kid, was designed and priced for the home market. An advertisement published in the New York Times just before Christmas in 1975 indicates that its small four-function instrument sold for only $15.00. The calculator had no display, but the keyboard was decorated with an image of an owl with two large eyes, one green and one red. Children entered both a problem and their answer to it. If the answer was correct, the green eye flashed reinforcement. If not, the red eye lit up. The ad proclaimed that “The Novus ‘Quiz Kid’ just might make a Whiz Kid out of Jr [sic]!”  At least it would “provide hours of fun and interest” (New York Times, December 23, 1975, 4.  Novus had entered the calculator business by buying out the calculator division of National Semiconductor, and some devices were sold as the National Semiconductor Quiz Kid). A report from late May of 1976 indicates that by then some 600,000 of the toys had been shipped (New York Times, May 23, 1976, F3).

Texas Instruments had responded to the popularity of four-function calculators by producing the Datamath 2500, and to the HP-35 with the SR-10. Its answer to the Quiz Kid and similar toys was the Little Professor. Introduced in mid-1976, it was a calculator that had been altered to present simple arithmetic problems to a child. A correct answer led to another problem, a wrong answer to the message “EEE.”  The keyboard was decorated with an image of a bewhiskered and bespectacled professor holding a book. Questions and answers appeared on a red LED screen that, in combination with the top of the instrument, looked like a mortar board. In early examples of the toy, the on-off switch was on the right side near the professor’s face, and looked rather like a tassel from a mortar board. The machine sold for about $18 early in 1977, with the price dropping to $13 by the middle of the year. The Little Professor sold in the millions.  It is produced, in modified form, to this day. The Quiz Kid and the Little Professor were later joined by a range of games that included Coleco Digits (ca. 1978), Invicta’s Electronic Mastermind (ca. 1980), and an Electronic Backgammon Game by Tyrom (ca. 1981).

Graphing Calculators

The first commercial graphing calculator was introduced by the Japanese firm of Casio Computer Company. Casio, founded in 1946, had sold electric desk calculators since the 1960s, and introduced a transistorized form of the machine in 1965. In the 1970s and 1980s, it released a variety of microprocessor-based consumer products including handheld calculators, digital watches, electronic musical instruments, and televisions.  Its fx-7000G graphing calculator, introduced in 1985, sold for a price that settled around seventy-five dollars. By the following year, it had been adopted by a program in Ohio schools, and other states soon followed.

Other calculator manufacturers soon took up the challenge of designing graphing calculators. In 1987, Hewlett-Packard Corporation introduced its HP-28C calculator. It featured not only graphing but symbolic manipulation, as well as limited integration and differentiation. Indeed, Hewlett-Packard soon was ready to launch a version of the HP-28C with expanded memory, known as the HP-28S. It chose to do so at the January 1988 centennial meeting of the American Mathematical Society. Those attending the annual banquet of the society traditionally received a useful trinket such as an alarm clock. At the centennial party, the favor was an HP-28S. It came with an extra charge of $60 (the banquet alone was $30). However, considering that the list price of the calculator was $235, the fee was not unreasonable. The example of the HP-28S shown was owned by Andrew Gleason, who was among those working on the reform of calculus teaching as part of the Harvard Consortium. Other manufacturers soon offered graphing calculators.

With the widespread availability of other handheld devices for communication and for access to the web, the role of the electronic calculator has changed. Within mathematics education, calculators are now sold as much for what they do not do as for what they do. That is to say, calculators do not allow students to spend time texting, web surfing, or consulting with unauthorized sources. They are sometimes built so as NOT to evaluate certain functions.  In the larger world, although inexpensive four-function calculators are still available for purchase, they also appear virtually on a desktop, laptop, and handheld computers.

This object group reflects the contributions of numerous donors to the Smithsonian Institution, and the work of numerous museum and library staff. A grant from the Lemelson Center for Invention and Innovation and generous assistance from scholars at the Whipple Museum for the History of Science at Cambridge University are gratefully acknowleged.


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