Editing IBM System/360 (section)

===Background===
By the early 1960s, IBM was struggling with the load of supporting and upgrading five separate lines of computers. These were aimed at different market segments and were entirely different from each other. A customer who purchased a machine to handle accounting, such as the [[IBM 1401]], that was now looking for a machine for engineering calculations, such as the [[IBM 7040]], had no reason to select IBM – the 7040 was incompatible with the 1401 and they might as well have been from different companies. Customers were frustrated that major investments, often entirely new machines and programs, were required when seemingly small performance improvements were needed.<ref name= gamble>{{cite web |url=https://www.ibm.com/history/system-360 |title=The IBM System/360: The 5-billion-dollar gamble that changed the trajectory of IBM|website=IBM}}</ref>

In 1961, IBM assembled a task force to chart their developments for the 1960s, known as SPREAD, for Systems Programming, Research, Engineering and Development. In meetings at the  New Englander Motor Hotel in [[Greenwich, Connecticut]], SPREAD developed a new concept for the next generation of IBM machines. At the time, new technologies were coming into the market including the introduction of replacement of individual [[transistor]]s with [[Integrated circuit|small-scale integrated circuits]] and the move to an 8-bit [[byte]] from the former 6-bit oriented words. These were going to lead to a new generation of machines, today known as the third generation, from all of the existing vendors.<ref name= gamble/>

Where SPREAD differed significantly from previous concepts was what features would be supported. Instead of machines aimed at different market niches, the new concept was effectively the union of all of these designs. A single [[instruction set architecture]] (ISA) included instructions for [[binary number|binary]], [[floating-point arithmetic|floating-point]], and [[binary-coded decimal|decimal]] arithmetic, string processing, conversion between character sets (a major issue before the widespread use of [[ASCII]]) and extensive support for file handling, among many other features.<ref name= gamble/>

This would mean IBM would be introducing yet another line of machines, once again incompatible with their earlier machines. But the new systems would be able to run all of the programs that formerly required different machines. A concern was that there was a risk that their customers, facing the purchase of yet another new and incompatible platform, would simply choose some other vendor. Yet the concept steadily gained support, and six months after being formed, the company decided to implement the SPREAD concept.<ref name= gamble/>

A new team was organized under the direction of [[Bob O. Evans|Bob Evans]], who personally persuaded CEO [[Thomas J. Watson Jr.]] to develop the new system. [[Gene Amdahl]] was the chief architect of the computers themselves, while [[Fred Brooks]] was the project lead for the software and [[Erich Bloch]] led the development of IBM's [[hybrid integrated circuit]] designs, [[Solid Logic Technology]].<ref name=bloch>{{cite news |url=https://www.nytimes.com/2016/11/30/technology/erich-bloch-who-helped-develop-ibm-mainframe-dies-at-91.html |title=Erich Bloch, Who Helped Develop IBM Mainframe, Dies at 91 |first=Sam |last=Roberts |date=30 November 2016 |newspaper=The New York Times}}</ref>