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IBM 603

The First Commercial Electronic Calculator

Long before electronic computers emerged, IBM was in the mechanical data-processing business, producing machines that counted, tabulated and measured in innumerable ways with gears, cogs and relays. The IBM ® 603 Electronic Multiplier, which made its debut in September 1946, was a milestone in the transition from mechanical to electronic computing.

The 603 was the world’s first mass-produced electronic calculator. It employed 300 vacuum tubes in its calculating unit, which was connected to an IBM Type 520 punch-read unit that fed numbers into the calculator and returned results back via paper card. Its calculating unit could multiply two six-digit numbers ten times faster than other calculating machines available at the time. The system could make as many as 6000 calculations per hour. Each multiplication operation was completed in 0.027 seconds, according to the IBM 603 official manual.

As the manual explained: “The Electronic Multiplier makes use of recently-developed electronic circuits which perform calculations at extremely high speeds. Thus the burdensome and usually slow-speed process of computing products is reduced to an automatic high-speed process.”

Commercial interest in the 603 came as something of a surprise to IBM. As recounted in The Maverick And His Machine: Thomas Watson, Sr. and the Making of IBM: “To IBM’s astonishment, customers liked the 603 and placed orders for it. Somewhat embarrassed by the 603’s limitations, Watson cut off production at 100, and the engineers built a more refined, versatile follow-up, the IBM 604 Electronic Calculating Punch. It used 1400 vacuum tubes and could perform simple equations. Over the next 10 years IBM would build and lease 5600 of the 604 machines. No one at IBM had predicted such success. For the first time, Watson [Jr.] got the message: Customers will buy electronic products.”

For Thomas Watson Jr., the founder’s son and future IBM president, the 603 was also a key personal milestone. It was his first executive project and something of a business gamble. He became the leading advocate for electronics products, and that vision guided him and IBM for the next 15 years.

The 603 also inspired innovation by companies that collaborated with IBM. In 1948, engineers at Northrop Aircraft were looking for ways to speed up some of the sophisticated calculations that took weeks to complete by hand. They borrowed a 603 and figured out how to connect it to an IBM Type 405 accounting machine to accelerate their work and print out results. IBM drew on the Northrop prototype to develop the IBM Card-Programmed Electronic Calculator (CPC) in 1949. By 1955, 700 CPCs capable of several thousand operations per second had been sold, largely to aerospace firms.

Looking back, the 603 was more than a technical first; it pointed the way to where IBM’s business was heading in the 1950s. The 603—and its quick successor, the 604—revealed a new, fast-growing market segment for scientific and engineering computing. Moreover, they made it clear that electronics would be at the heart of that future. The era of electromechanical computing would soon give way to fully electronic devices based on vacuum tubes, transistors and integrated circuits.