18. Hand-held electronic calculators were a product of 1970
Before the advent of calculators, engineers, architects, designers, technicians, scientists, and mathematicians used slide rules to resolve difficult equations. In 1970, the first electronic handheld calculators appeared. Hand-held was a bit of a misnomer, they were large – far too large to fit in a pocket – but they were portable. The first calculators were marketed by Bowmar and Canon, and used chips from Texas Instruments. Another marketed by Busicom used chips from Mostek. None of them could perform functions except add, subtract, multiply, and divide. They were limited in the number of decimal places they could handle (12) and they had no screen on which to view the results.
The calculators relied on thermal paper to deliver the results of its use to the user. Numbers were literally burned onto the paper which was fed over a printer head. Thermal paper was sold separately, and was not known for being inexpensive. Batteries were rechargeable, and how long they could hold a charge depended on the length of use (as well as ambient temperature). Most professionals regarded calculators as little more than a novelty and continued to rely on their trusty slide rules. Within two years calculators appeared which were smaller, more reliable, had screens as well as printers, and could perform trigonometric functions. The personal computer wasn’t far behind.