On 15 April 2017 at 17:27, Phil Smith <[email protected]> wrote: > > What others? No credit for things like DDR or ICKDSF, which, while IPLable, > aren't really "OSes" in any kind of real sense!
Maybe even closer to the line are GCS (under VM/370's and later CP only, but could in theory run standalone with some mods), and HRTPB360 (the standalone RJE multileaving program buildable for S/370 20 or S/360 30+). Bizarrely, despite that BiSynch support has been gone for around 20 years, and that the last machine that could IPL it was sold probably around 1990, HRTPB360 is still distributed in source form in SYS1.SAMPLIB on z/OS. It's byte for byte identical to the version distributed with HASP for MVT and MVS/370, and will IPL in a suitable virtual machine or emulator. Lest someone suggest that HRTPB360 is not an operating system, I was able to make some minor mods to it in the 1970s to support some additional function, and it was certainly possible to treat it as one. The "dispatcher", such as it is, in HRTPB360 was called the "commutator" by analogy with an electric motor https://en.wikipedia.org/wiki/Commutator_(electric) and was essentially a branch table in a loop where NOPs were changed to and from branches as a form of POST when a particular function needed to be run. Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
