1964

IBM System/360

Gene Amdahl (1922–2015), Fred Brooks (b. 1931)

In 1950, IBM had made just four different kinds of electronic computers—and two of them were prototypes. Ten years later, IBM was manufacturing more than a dozen different computer families, with more than 10,000 systems delivered to customers.

IBM defined the catastrophe of success: it had five separate product lines, each with its own design, instruction set, and operating system. Hardware and software created for one line could not run on any of the others. IBM’s solution was a radical, bet-the-company gamble called System/360. The idea was to create a single computer architecture that would allow software to run across the whole range of IBM computer systems, from the smallest to the largest.

Work on System/360 started in secret in 1959 and involved IBM laboratories and plants throughout the world. Fred Brooks was the project manager; Gene Amdahl was the project’s chief architect. They oversaw teams that created six different-but-compatible computer lines that could support 19 combinations of speed and memory, with the fastest running roughly 50 times faster than the slowest. It had no tubes: System/360 was based entirely on the company’s integrated circuits. Memory size ranged from 8,000 to 8,000,000 characters of magnetic core.

System/360 was announced on April 7, 1964, simultaneously in 165 cities: more than 100,000 people attended. The first customer system shipped in 1965.

Originally estimated to cost just $675 million, the company ending up spending $750 million on engineering alone and then another $4.5 billion on factories, equipment, and the machines themselves, which were typically rented to customers at a cost of between $5,330 per month for a System 30 to $115,000 per month for the largest systems, called mainframes. Just one year after the first system shipped, System/360 had generated $1 billion in pretax profit; annual profits more than doubled by 1970, when IBM replaced System/360 with upward-compatible System/370.

Brooks was awarded the 1999 A.M. Turing award for his work “on computer architecture, operating systems, and software engineering.”

The IBM System/360 Model 30 computer. The first Model 30 was purchased by McDonnell Aircraft Corporation and was the least expensive of the System/360 models shipped in 1965.