Microcode and Backwards Compatibility

The release of the IBM System/360 represents a major milestone in the history of computing. In 1964 IBM announced the 360 as the first family of compatible computers. Users could choose a system that was just the right size for their needs, mix and match peripherals, and have no fear of future upgrades. If you started on a low-end 360 you could move up to a top of the line model and keep all your software! Something like this had never been done before. Such a watershed moment resulted in interesting cascading effects. In this episode we will look at the 360 itself. In the coming weeks we will be examining how it shaped and dominated the market, how it led to a federal antitrust suit, and how a mysterious series of clone computers survived in uncertain times.   Selected Sources:   https://spectrum.ieee.org/building-the-system360-mainframe-nearly-destroyed-ibm   https://archive.computerhistory.org/resources/access/text/2012/11/102658255-05-01-acc.pdf - Fred Brooks Oral History   https://archive.computerhistory.org/resources/access/text/2017/11/102655529-05-01-acc.pdf - 14K Days