In many ways, the modern computer era began in the New Englander Motor Hotel in Greenwich, Conn. It was there in 1961 that a task force of top IBM engineers met in secret to figure out how to build the next-generation IBM computer.
A new design was sorely needed. IBM already sold a number of successful though entirely separate computer lines, but they were becoming increasingly difficult to maintain and update.
"IBM in a sense was collapsing under the weight of having to support these multiple incompatible product lines," said Dag Spicer, chief content officer for the Computer History Museum, which maintains a digital archive on the creation and success of the System/360.
Fifty years ago on April 7, IBM announced the computer that the task force had designed, the System/360. The system eventually became a huge success for the company -- and a good thing too. IBM's president at the time, Tom Watson, Jr., killed off other IBM computer lines and put the company's full force behind the System/360. IBM's revenue swelled to $8.3 billion by 1971, up from $3.6 billion in 1965. Through the 1970s, more than 70 percent of mainframes sold were IBM's. By 1982, more than half of IBM's revenue came from descendants of the System/360.
But its impact can be measured by more than just the success it brought to IBM. "IBM was where everyone wanted to work," said Margaret McCoey, an assistant professor of computer science at La Salle University in Philadelphia, who also debugged operating system code for Sperry/Univac System/360 clones in the late 1970s.
The System/360 ushered in a whole new way of thinking about designing and building computer systems, a perspective that seems so fundamental to us today that we may not realize it was rather radical 50 years ago. Before the System/360 introduction, manufacturers built each new computer model from scratch. Sometimes machines were even built individually for each customer. Software designed to run on one machine would not work on other machines, even from the same manufacturer. The operating system for each computer had to be built from scratch as well.
The idea hatched at the Connecticut hotel was to have a unified family of computers, all under a single architecture. Gene Amdahl was the chief architect for the system and Fred Brooks was the project leader.
Amdahl would later coin Amdahl's Law, which, roughly stated, holds that any performance gains that come from breaking a computer task into parallel operations is offset by the additional overhead incurred by managing multiple threads. And Brooks would go on to write "The Mythical Man Month," which asserted a similar idea that adding more people to a software development project can actually slow development of the software, due to the additional burden of managing the extra people.
The idea they came up with was to have a common architecture shared among the lower-end, less expensive machines and the priciest high-speed models. The top-end models would perform 40 times as fast as the low-end models. Keep in mind that applying the word "architecture" to the design of a computer was all but unheard of in the early 1960s.