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Yes, CICS came to my mind. But CICS is not an operating system, it needs one to be run AFAIK. The Wikipedia article says it runs under VM/MVS or VM/VSE. OS/360

Yes, CICS came to my mind. But CICS is not an operating system, it needs one to be run AFAIK. The Wikipedia article says it runs under VM/MVS or VM/VSE. OS/360 was discontinued. MVS is listed as one of its successors. So I believe, while interesting, the VM/CMS emulator/simulator mentioned above is only representing System/370 period, not System/360. I am certainly not an expert on the matter. Edit: Following a couple of Wikipedia links tells that in the 360 period something called CM/CMS existed. It seems only loosely related to the VM/CMS used in the 370 period. Edit 2: For an emulator see https://en.m.wikipedia.org/wiki/Hercules_(emulator) https://en.m.wikipedia.org/wiki/Hercules_(emulator) Edit 3: https://en.m.wikipedia.org/wiki/History_of_IBM_mainframe_operating_systems https://en.m.wikipedia.org/wiki/History_of_IBM_mainframe_ope... seem worth reading. The 360 chapter links nicely to TFA, e.g. The Mythical Man-Month.

deleted 3y ago
[deleted]
p_l 3y ago
VM/CMS from my understanding started in System/360 period, but it was not really something advertised - initial versions ran on specific models only, and even later on it wasn't necessarily available to officially purchase.
- usr1106 3y ago
  I don't think virtual memory existed on the 360. The unofficial OS provided to some important customers dissatisfied with the nightmare delays in OS/360 was CM/CMS. Maybe the CM/CMS command line experience was already rather similar, I don't know. Virtual memory did not even exist in the first S/370 models, that was a slightly later feature. Disclaimer: Thinking is different from knowing :)
  - p_l 3y ago
    The origin point was, according to my searches, specially modified S/360-40, where CP-40 (VM's "grandpa") was developed as well as CMS. This was followed by S/360-67 which introduced address translation to S/360 and was specially built for timesharing - there, CP-67 was developed, and since model 67 was sold normally, it was apparently provided to some customers as alternative OS. CP-67 evolved into VM/370
    - usr1106 3y ago
      Yeah, when reading VM I thought too much about virtual memory. But IBM famously never used the term memory, but called it storage. So VM probably only referred to Virtual Machine. So their first virtual machines including all during 360 era, probably still showed physical adresses, even if more than one virtual machine could using the same addresses exist. None of them had page tables, they all had the same addresses. First MVS (multiple virtual storages) changed that.
      - rbanffy 3y ago
        Mainframes notably call memory “storage”, so virtual memory becomes “virtual storage”. The idea of virtual machines in mainframes is closely tied to user logins as you get “your own” machine on logon. IBM mainframes diverged from the OS tree very early on and evolved similar services, but with very different conceptual frameworks.

deleted 3y ago

[deleted]

p_l 3y ago

VM/CMS from my understanding started in System/360 period, but it was not really something advertised - initial versions ran on specific models only, and even later on it wasn't necessarily available to officially purchase.

usr1106 3y ago
I don't think virtual memory existed on the 360. The unofficial OS provided to some important customers dissatisfied with the nightmare delays in OS/360 was CM/CMS. Maybe the CM/CMS command line experience was already rather similar, I don't know. Virtual memory did not even exist in the first S/370 models, that was a slightly later feature. Disclaimer: Thinking is different from knowing :)
- p_l 3y ago
  The origin point was, according to my searches, specially modified S/360-40, where CP-40 (VM's "grandpa") was developed as well as CMS. This was followed by S/360-67 which introduced address translation to S/360 and was specially built for timesharing - there, CP-67 was developed, and since model 67 was sold normally, it was apparently provided to some customers as alternative OS. CP-67 evolved into VM/370
  - usr1106 3y ago
    Yeah, when reading VM I thought too much about virtual memory. But IBM famously never used the term memory, but called it storage. So VM probably only referred to Virtual Machine. So their first virtual machines including all during 360 era, probably still showed physical adresses, even if more than one virtual machine could using the same addresses exist. None of them had page tables, they all had the same addresses. First MVS (multiple virtual storages) changed that.
    - rbanffy 3y ago
      Mainframes notably call memory “storage”, so virtual memory becomes “virtual storage”. The idea of virtual machines in mainframes is closely tied to user logins as you get “your own” machine on logon. IBM mainframes diverged from the OS tree very early on and evolved similar services, but with very different conceptual frameworks.