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IBM 608 calculator

The IBM 608 calculator - 1955.

The IBM 608 calculator - 1955.
The IBM 608 calculator (shown at left) was the first completely transistorized computer available for commercial installation. Announced in April 1955, the 608 began the transition of IBM's line of small and intermediate electronic calculators from vacuum tube to transistor operation. It contained more than 3,000 transistors -- tiny germanium devices no bigger than a paper clip -- and magnetic cores -- doughnut-shaped objects slightly larger than a pinhead, in the first known use of transistors and cores together in a computer. The magnetic cores could remember information indefinitely and recall it in a few millionths of a second, and made up the machine's internal storage or memory.

The 608's transistors made possible a 50 percent reduction in physical size and a 90 percent reduction in power requirements over comparable vacuum tube models. The machine could perform 4,500 additions a second, a computing speed 2.5 times faster than IBM's Type 607 calculator introduced only two years before. It could multiply two 9-digit numbers and derive the 18-digit product in 11 one-thousandths of a second, and divide an 18-digit number by a nine-digit number to produce the nine-digit quotient in just 13 one-thousandths of a second. The associated IBM 535 card read punch (shown at right) was used for both input and output, and was designed to permit a card to be calculated and the results punched while passing through the machine at the rate of 155 cards per minute.

In 1957, customers could purchase the 608 for $83,210 (or rent it for $1,760 a month) and the 535 for $44,838 (or rent it for $715 a month). The 608 was withdrawn from marketing in April 1959. (VV2214)