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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/
by 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 agoThe 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 agoYeah, 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 agoMainframes 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.