[email protected] (Shmuel Metz , Seymour J.) writes: > The B2 opcodes came later. Some of the emulator features on the S/360 > had longer opcodes.
diagnose (x'83') is supervisor instruction defined as model specific. common mechanism was the displacement field was used as "extended op-code" ... selecting specific/specialized microcode functions. one use was invoking microcode emulators (available on various 360 processors) diagnose displacement x"3cc" selects emulator function, turning on/off special emulator instructions (x'99' opcode) ... page 64. http://www.bitsavers.org/pdf/ibm/360/1401_emulator/GC27-6940-4_360_1401emul.pdf and then more/other diagnose variations on page 72. recent post (in afc) discussing above http://www.garlic.com/~lynn/2011h.html#16 Is the magic and romance killed by Windows (and Linux)? as undergraduate in the 60s ... i made a whole bunch of enhancements to cp67. one was special fast dasd ccw for cms file i/o. the guys at the science center slammed me for violating 360 principles of operations ... since such a mechanism wasn't defined for real hardware. they came up with definition that all such special (virtual machine) processing had to be done via "diagnose" instruction using the "fiction" that it virtual machines running under cp67 qualified as a special model (aka conforming to 360 principle of operations as implementation being model specific, in this case, the "virtual machine" model). this kicked off a whole slew of special virtual machine functions (aka "instructions") all selected via the diagnose instruction displacement field. cp67 cms (cambridge monitor system) would run on real 360 ... and as some of the specifial virtual machine features were added, at startup, cms would check for running on real machine or virtual machine (setting switch for using straight real machine processing or optional virtual machine processing). in the morph to vm370, cms was renamed to converstational monitor system and the ability to run on real hardware was crippled. misc. past posts mentioning cambridge science center http://www.garlic.com/~lynn/subtopic.html#545tech -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- 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
