hal9...@panix.com (Robert A. Rosenberg) writes: > No Bill is right. OS/VS2 Release 2 WAS MVS like OS/VS2 Release 1 was > SVS. SVS was OS/360 MVT with Virtual Addresses (SVS was a single 16MB > Address Space with which was divided into smaller areas for the > programs to use, just like MVT). MVS made the program's area into > duplicate address ranges which sat between and shared the low and high > address ranges which belonged to the Operating System.
old post about os/vs2 release 1 (svs), release 2 (mvs), and glide path to release 3 ... operating system for future system http://www.galric.com/~lynn/2011d.html#73 past future system posts http://www.garlic.com/~lynn/submain.html#futuresys really long-winded post about the transition to MVS and pointer-passing API causing enormous problems ... involved image of MVS occupying 8mbytes of every application virtual address space ... in order for kernel code to access application data ... and common segment for passing data between applications and semi-priviledged subsystems now in separate virtual address spaces ... and there needing to be sufficient sized common segment to handle all applications & subsystems ... larger installations were having common segment threatening to increase to 6mbyte ... leaving only 2mbytes for application in every "private" 16mbyte virtual address space. http://www.garlic.com/~lynn/2012b.html#66 3081 & 370xa with 31bit addressing was taking so long to get out after future system failure ... that dual-address space was retrofitted to 3033 in attempt to somewhat alleviate the common segment pressure on what little was left for application use out of 16mbytes. some discussion getting out 3081 (and eventually 31bit addressing) after future system failure http://www.jfsowa.com/computer/memo125.htm -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
