I would guess most basic applications and simple system utilities from OS/360 will run unchanged, even in load module form. If you have an IEBCOPY dump on a medium you can read I would guess you could restore it and run it under z/OS V2R4.
That's pretty new source code you show. <g> I don't think of RMODE/AMODE as old stuff, but I guess it is all relative. Certainly the code you post below (if completed) would assemble, link and run without error. It *is* quite an achievement. I am personally perhaps counter-usual-wisdom in that I wonder if the 100% slavish compatibility was an over-learning of the lessons of Future System on IBM's part. I wonder if the guaranteed compatibility has given customers permission to ignore the platform in their management thought process. "It will always work whether we invest in it or not." https://en.wikipedia.org/wiki/IBM_Future_Systems_project if you don't know what I am referring to, especially the last paragraph under Project End. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Rupert Reynolds Sent: Monday, December 16, 2019 12:48 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Backward compat--how far? Another question, purely out of interest: Can the old MVS/SP code still run unchanged? I reminisced with a friend about the day he whinged about a 64k code segment size on Intel micros and I out-whinged him with a 4k code CSECT :-) Can a modern z/OS installation still assemble, link and run the old stuff, such as the typical local utilities we all saw: MYPROG CSECT MYPROG RMODE ANY MYPROG AMODE 24 STM 14,12,12(13) USING ... If so, that's quite an achievement, both in the changes and the flexibility of the original design! ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
