You're right. I had forgotten about the S/360 model 67. Most of the 360s in production were not model 67s, however. Certainly all the 360s which I knew anything about were non-virtual 360s. The first virtual storage-capable processor I ever saw and touched was in 1974 running SVS. So what was the correct term for non-virtual storage way back then for non-67 models of the S/360? Storage? Real storage? V=R storage? The terms I heard most frequently included the word "core." Bill Fairchild
----- Original Message ----- From: "Lynn Wheeler" <[email protected]> To: [email protected] Sent: Wednesday, February 19, 2014 9:51:08 AM Subject: Re: assembler [email protected] (DASDBILL2) writes: > Since virtual storage is now so much less expensive and so much more > available than storage [1] was 50 years ago, why not be > really extravagant and use one whole byte per store? If the byte > contains 0, then the store number is not valid, or something like > that, and if the byte contains anything other than 0, then the store > number is valid. This should result in much simpler code to > access this table. > Bill Fairchild > Nolensville, TN > > [1] In those days, there was no virtual or real storage available on > IBM's mainframes. There was only "storage". account of justification for moving MVT to virtual memory aka MVT had significant efficiency issues with storage allocation, move to virtual memory would allow running 16 concurrent tasks in 1mbyte machine with little or no paging (MVT typically only used 25% of storage in region) http://www.garlic.com/~lynn/2011d.html#73 Multiple Virtual Memory as aside, 360/67 was modified 360/65 with addition of hardware virtual memory ... originally intended for tss/360 ... tss/360 never did reach production quality ... so a lot of places would run them in straight 360/65 mode. However univ of michigan wrote their own virtual memory operating system, MTS. Stanford also wrote their own virtual memory system Orvyl (where Wylbur editor was originally implemented). and of course the science center did virtual machine cp67 ... some past posts mentioning cp67 http://www.garlic.com/~lynn/subtopic.html#545tech actually the science center got a 360/40, made their own hardware modifications to support virtual memory and did cp40 .... pending availability of 360/67 (at which time, cp40 morphs into cp67). even tho MVT move to virtual memory ... initially SVS (later morphs into MVS), was planning on doing little actual paging ... their design of page replacement algorithm was still important ... and I got into a big argument that they had done some things very wrong. It wasn't until well into MVS product cycle that somebody realized how wrong ... it turns out that they were selecting non-changed, high-use, shared linkpack pages for replacement ahead of selecting lower use, private, changed data pages. An example of horrible use of storage locality was the initial port of APL\360 to CP67/CMS for CMS\APL. In the APL\360 environment, workspaces were typically 16kbytes (or sometimes 32kbytes) and a complete workspace was swapped as whole unit ... so locality of use played little importance. However, CMS\APL had workspace was large as virtual memory. The original APL\360 implementation would allocate a new storage location for every assignment ... and when it completely exhausted workspace ... it would do garbage collection and collect all data to contiguous area of storage ... and then start again. Even a small APL program could repeatedly touch every available workspace storage location. In the APl\360 swapping environment this was hardly noticed. In CMS\APL demand page environment with workspace as large as virtual memory ... as "small" APL program would through the machine into "page-thrashing". As part of the creation of CMS\APL ... the APL\360 storage management had to be redone to make it extremely virtual memory friendly. trivia ... CMS\APL with large-sized workspaces and also introduced an API for accessing system services ... like file read/write ... allowed use for real-world applications. One such was Armonk business planners used it for modeling IBM business .... loading the most valuable of corporate assets (all the customer details) on the science center cp67 and using it remotely from Armonk. This also required some amount of security ... since the science center machine was also in use by students&staff at various Cambridge/Boston educational institutions. Being able to do real-world applications in CMS\APL gave rise to the HONE system for world-wide sales&marketing support ... some past posts mentioning HONE &/or APL http://www.garlic.com/~lynn/subtopic.html#hone the science center was also on the forefront of performance modeling, performance monitoring, workload & system profiling, etc ... some of which later evolves into things like capacity planning. One of the tools started out using the REDCAP full instruction trace program from POK to capture all instruction/storage fetch&store refs and model it for things like locality of reference in virtual memory paged environment. This was used as aid in moving apl\360 to cms\apl. As it got more sophisticated, it was used for semi-automated program reorganization for improved operation in virtual memory environment. Several of the large OS/360 application development groups also started using it as part of their move from MVT real-storage to virtual memory environment (also was used for simple "hot-spot" monitoring). This was eventually released to customers as "VS/Repack" product. A lot of the work that was done in the 60s and 70s for optimizing throughput in virtual memory environment is now applicable for optimizing throughput in processor cache environment. -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
