[email protected] (Gabe Goldberg) writes:
> One response cited Wikipedia entry. ALSO good timing; I'm ALSO writing
> article on VSE community.  As you'd expect, the VSE list has had a lot
> to say -- positive, negative, and informative.

OS/360 for a time PCP, MFT, and MVT ... but didn't work well in the
smallest real memory configurations ... giving rise to DOS/360.  OS/360
somewhat becomes split between MFT customers (usually mid-size memory
configurations) and MVT (largest memory configurations).

Move to virtual memory, DOS/360 morphs into DOS/VS (singe virtual
address space, MFT morphs into VS1 (single virtual address space) and
MVT morphs into VS2 (initially with single virtual address space, aka
SVS much like VS1 ... and eventually MVS with multiple virtual address
spaces).

During the Future System period, 370 efforts are being killed off (FS
was different than 360/370 and was going to completely replace it).
With the demise of FS, there is mad rush to get products back into the
370 pipeline. POK kicks off 3033 (168 logic mapped to 20% faster chips)
and 3081 & MVS/XA in parallel (and convinces corporate to kill off vm370
product and move all the people to POK to work for MVS/XA; Endicott
eventually acquires the vm370 product mission, but has to recreate a
development group from scratch).

While POK is doing "XA" architecture ... highly tailored to MVS ...
Endicott kicks off the "E" architecture ... which in large part is
moving the single virtual address space into microcode and new
instructions that enable/disable virtual page for specific real page.
Internally the 4331 is called E3 and 4341 is called E4. DOS/VS becomes
DOS/VSE.

In part because large percentage of 4300 machines are run with vm/370
... they are actually run in 370 mode ... supporting 370 multiple
virtual address spaces.

os/vs1
https://en.wikipedia.org/wiki/OS/VS1

above slightly garbled since the migration aid was primarily motivated
for helping move mvs/370 to mvs/xa

VSE
https://en.wikipedia.org/wiki/VSE_%28operating_system%29

The migration aid originally was only going to be used for internal
mvs/xa development and never released to customers and so paid little
attention to general function and performance. There then is internal
politics ... an internal datacenter added full XA support to VM370 with
full function/performance. POK wants corporate to support a massive new
staff for the migration aid to try and upgrade it to the feature and
performance of standard vm370 (with XA added). POK wins.

-- 
virtualization experience starting Jan1968, online at home since Mar1970

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