On Tue, 29 Jan 2008 10:47:05 -0500, Anne & Lynn Wheeler wrote: >... there was even some speculation that one of the other clone >> processor vendors creation of "macrocode" was to enable them to quickly >> adapt to such things (be more agile in tracking, implementing, deploying >> changes).
There may have been speculation within IBM that Macrocode, and the architecture that enabled it, was to make it easier to develop new features. I can tell you that I was at Amdahl at the time working on the 580. That was definitely a major reason for it. > >actually such speculation dates back three decades to the introduction >of cross-memory instructions and dual-address space mode on 3033 With the introduction of MVS/SE, Amdahl provided something called SE Assist, which provided software emulation of the new instructions that SE used. There was also a ZAP to NIP to no-op a TPROT instruction that seemed to be there only to prevent MVS/SE from IPLing on a processor without the new instructions. When the 580 was being designed, the enhanced architecture of the processor allowed for such software emulation of new instructions in Macrocode without having to install code in the operating system. This allowed instructions in NIP to be emulated. The 580 also had an advanced channel architecture that made it much easier to implement the XA I/O subsystem. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
