The Xerox Alto had a custom CPU that used microcode extensively - the CPU actually did most system management tasks like re-blitting the entire screen for every

The Xerox Alto had a custom CPU that used microcode extensively - the CPU actually did most system management tasks like re-blitting the entire screen for every new frame and managing disk I/O, and only when it wasn't handling these scheduled tasks did it execute an "emulation" task that actually executed arbitrary code. More info: http://www.righto.com/2016/09/xerox-alto-restoration-day-5-smoke-and.html http://www.righto.com/2016/09/xerox-alto-restoration-day-5-s... Start of story (the part 1 link is not easy to find): http://www.righto.com/2016/06/restoring-y-combinators-xerox-alto-day.html http://www.righto.com/2016/06/restoring-y-combinators-xerox-...