Early HP-35 adverstisement, c. 1972
Credit: Hewlett-Packard Company Archives

Calculators

All desktop calculators prior to the 1960s were mechanical. By the mid-twentieth century most had keyboards and were powered either by the depression of keys or with a crank. The invention of the integrated circuit in 1971 fostered the electronic calculator revolution. By 1974, an electronic calculator costing less than $50 was more powerful than its mechanical equivalent costing $1,500 or more. As a result, manual slide rules, favored by scientists and engineers, quickly became obsolete. Today many electronic calculators are small, sophisticated programmable computers with more power than the mainframes of 40 years ago.