history is hard

Dave Wade dave.g4ugm at gmail.com
Fri May 29 17:57:15 CDT 2020

Phil (and the rest of you)

You may find this interesting:-


note that you won't find VMSHARE articles via google. The site isn't indexed
anywhere else.


> -----Original Message-----
> From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Phil Budne via
> cctalk
> Sent: 29 May 2020 23:39
> To: cctalk at classiccmp.org
> Subject: Re: history is hard
> > From: Noel
> >     > From: Jon Elson
> >
> >     > As far as I know, there was no VM/360. There WAS VM/370, which was
> out
> >     > in the early 1970's
> >
> > CP/67, which was a semi-product, and ran only on 360/67's, was
> > basically the same functionality as VM/370. (I get the impression that
> > the code was descended from CP/67, but I can't absolutely confirm that
> > - although see Varian, below.)
> In the last decade worked with another contractor (whose name I have
> thankfully forgotten: after he removed a purely symbolic layer of
> in my code, and when I explained why it was there (to allow hardware
> operations to be specified in a platform independent way, to make it easy
> move the system to new hardware) tritely
> replied: "if wishes were fishes") who made it ABUNDANTLY clear to me that
> VM/370 was significantly different from CP-67. Aw rats, found his
> name: Dave Tuttle.
> FWIW, on VM/370 being a reimplementation:
> https://en.wikipedia.org/wiki/CP/CMS says:
> 	In 1972, IBM announced the addition of virtual memory to the
> 	S/370 series, along with the VM/370 operating system, a
> 	reimplementation of CP/CMS for the S/370.
> also
> 	IBM reimplemented CP/CMS as its VM/370 product line, released
> 	in 1972 when virtual memory was added to the S/370
> 	series. VM/370's successors (such as z/VM) remain in wide use
> 	today. (It is important to note that IBM reimplemented CP-67,
> 	as it had CP-40, and did not simply rename and repackage
> 	it. VM coexisted with CP/CMS and its successors for many
> 	years. It is thus appropriate to view CP/CMS as an independent
> 	OS, distinct from the VM family.)
> and
> 	hypervisor: a mechanism for paravirtualization. This term was
> 	coined in IBM's reimplementation of CP-67 as VM/370.
> > One version of CP/67 provided a /370 virtual machine; it was used
> > extensively by the MVS development team. CP/67 was also brought up on
> > /370 hardware.
> To amplify: My introduction to "how wonderful VMs are" were was when I
> worked at BU (after leaving DEC) and told story of how CP or VM was ported
> to new hardware by running a second level VM (on a production
> system) that simulated the new hardware, and then VM for the new
> hardware could be booted in a THIRD level VM.  (As a DECie I was dubious
> about such things, tho they could have helped me debug TOPS-20 monitors
> in daylight, as opposed to waiting to take BUCS20 standalone at night).
> Maybe this is it, on pdf page 30, document page 28 of Varian's paper:
> http://www.leeandmelindavarian.com/Melinda/25paper.pdf
>     Alain Auroux did most of the actual coding and testing for the
>     bootstrapping, but Rip Parmelee, Bob Adair, and Charlie Salisbury
>     were also heavily involved in working out the design.  When Auroux
>     started, Cambridge was running a 360/67, not a S/370, and that 67
>     was a production system, so he had to avoid destabilizing it.
>     ?Vanilla? CP-67 systems created System/360 virtual machines, but
>     they did not virtualize the 360/67; that is, they did not allow a
>     guest to create its own virtual storage.  Auroux?s first step was
>     to modify CP-67 to create virtual 360/67s, which used 4K pages and
>     1M segments.  Once he had convinced the Cambridge Operations
>     Manager torun that as the production system, he could then proceed
>     to develop a CP-67 that virtualized theSystem/370 architecture.
>     The System/370 relocation architecture was different from the
>     360/67 architecture; it allowed both 2K and 4K pages and both 64K
>     and 1M segments.  So, Auroux modified his modified CP-67 to
>     support 64K segments and the new System/370 instructions.  He ran
>     that system second-level, so he could run a virtual S/370
>     third-level.  He developed a prototype ?CP-370? in that
>     third-level virtual machine.  Then, to test this CP-370?s
>     virtualization of System/370 virtual memory, he had to run it both
>     third- and fourth-level, with a couple of CMS machines running
>     fifth-level.  He remembers doing much of his testing from home at
>     night using an ?old, slow, noisy teletype?. His prototype CP-370
>     had been debugged in simulation by the end of 1970.  Late in
>     January, 1971, just before Auroux was to return to France, he
>     and Bob Adair and Rip Parmelee took copy of his system to Endicott
>     so that they could test it on a prototype 370/145 with relocation
>     hardware.  It IPLed the first time
> My recall was that they booted (sorry, IPL'ed) on the real hardware before
> any of IBM's "real" operating systems did.
> This may be it, in footnote 91, which spans across two pages(!), starting
> BEFORE the previous paragraph:
>     An IBM newsletter announced the awards given for the
>     virtualization of System/370 on the 360/67 (?Cambridge Men
>     Modified CP-67, Providing Tool for Developers?, IBM News,vol. 9,
>     no. 15, August, 1972, p. 1.):
>       CAMBRIDGE, MASS.: The work of four men at the Scientific Center
>       here begun almost two years ago had an important role in the
>       development of the operating systems announced this month.  The
>       four have received Outstanding ContributionAwards for their
>       work.  Two of the men, Dr.  Richard Parmelee and Alain Auroux,
>       are now with IBM France in Paris and Grenoble.  Charles
>       Salisbury and Robert Adair remain with the Scientific Center
>       staff.
>       The four extended and enhanced CP-67, the control program that
>       provided virtual machine capability on a Model 67.  Their
>       enhancement of the program gave IBM developers access to virtual
>       370s on a Model 67 as well as a version of CP-67 which would run
>       on System/370. The central modifications to the program made by
>       the IBMers were: support of the new dynamic address translation
>       facility, additional control registers, and some of the new 370
>       instructions and features.  It became a tool for many IBMers
>       writing the new virtual machine and virtual memory operating
>       systems.  Their extensions provided a means of testing 370
>       programs on Model 67 hardware even before 370 hardware was
>       available internally.
>       ?Moving CP-67 from a 360 base to a 370 base meant that the
>       CP/CMS Development Group working on VM/370 had something to
>       start running on their 145?, explains Dr.  William Timlake,
>       Scientific Center manager.  ?The people in SDD writing VS code
>       also had something to use in developing virtual memory
>       software.?  In mid-1970, an SDD advanced system programming team
>       headed by Russ Hamrick asked the four to assist in developing a
>       virtual machine system for the 145.  ?We obtained the
>       architectural specifications of the 370 advanced functions and
>       together developed the initial code?, notes Adair.
>       Two prototype systems resulted: one to provide virtual 370s on
>       the 67 (required for testing, since the advanced hardware was not
>       available), the other to provide virtual machines on a
>       System/370.
>       A critical test of the modified program came whenAuroux
>       travelled to Endicott to try the program on a prototype Model
>       145.  ?That was one of high points?, recalls Salisbury.  ?Auroux
>       loaded the disk pack onto theengineering model, a computer that
>       had never run an advanced function operating system, and the
>       system ran successfully.  It demonstrated that software could
>       be developed on a virtual machine for hardware not yet produced.?
>       After that, use of the modified CP-67 programs spread to several
>       locations where development activity was underway.
> More of the bloody history of how IBM was dragged into time sharing is
> outlined at:
> https://en.wikipedia.org/wiki/IBM_System/360_Model_67
> https://en.wikipedia.org/wiki/IBM_CP-40
> (as always veracity is dubious at best).
> Yes, history is hard!
> I think it's hard to get across how alien a concept VM was to those like
> who came from small(er), interactive computers.  IBM systems were large,
> and expensive, were great at doing bulk disk I/O (rigidly laid out on
disk), but
> terrible (or at least uninterested) in handling anything as interactive as
> character at a time terminals.
> VMs on commodity hardware didn't gain traction for maybe a quarter
> century after the original "CP/CMS" work.

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