edgould1...@comcast.net (Ed Gould) writes: > Remember the *OLD* days there was a 16MB max on (even) an MP? Never > mind the cost of $10K per meg (if memory serves me on a 168). > Yes the newer machines have more memory but in reality you really > don't get all that more functionality, and yes there are bells and > whistles for the z genation.
Significant MVS bloat by 3033 was causing a number of problems ... real storage requirements was banging hard at the 16mbyte limit. 16bit 370 PTE was 12bit (4kbyte) page number, 2defined bits and 2undefined/unused. They took 2undefined/unused bits then used them to prefix the (real) page number ... allowing 14bit page number or up to 64mbytes of real pages ... allowing lots of application virtual pages to reside above the 16mbyte line. os/360 significant pointer passing API paradigm was making 16mbyte virtual address space limit a problem. Transition from SVS to MVS gave each application its own 16mbyte virtual address space ... but pointer passing API paradigm required 8mbyte image of the MVS kernel in each application virtual address space. Then because subsystems services were in their own virtual address space, pointer passing API required 1mbyte CSA (in each virtual address space) for passing parameters. CSA size requirements were proportional to subsystems and applications ... for large 3033s was 5-6mbytes and threatening to become 8mbytes (leaving none for applications). Subset of "access registers" was then retrofitted to 3033 as dual-address mode (allowing subsystems to access application virtual address space w/o needing CSA). problem was that 4341 clusters had more processing power than 3033, more aggregate memory and I/O throughput, much lower cost and significantly less physical and environmental footprint. Folklore is that head of POK felt so threatened that corporate was convinced to cut allocation of critical 4341 manufacturing component in half. 4341 had significant improvement price/performance as well as physical and environmental footprint resulted in corporations ordering hundreds at a time for placing out in departmental areas ... sort of the leading edge of distributed computing tsunami. Before 4341s shipped, I got roped into benchmarking engineering 4341 for national labs for big compute farm ... sort of the leading edge of the coming supercomputer paradigm internet+distributed computing+compute farms ... evolves into cloud with hundreds of thousands of systems and millions of processors in each cloud megadatacenter (system&software costs have dropped to such a level that power&cooling are starting to dominate cloud costs). old email about air force data systems coming out to talk about 20 4341s, spring of 1979 (they had a few mainframes in their datacenter), but by the time they got around to caming out fall of 1979, it had jumped to 210 4341s. http://www.garlic.com/~lynn/2001m.html#email790404 and http://www.garlic.com/~lynn/2001m.html#email790404b other 4341 related email http://www.garlic.com/~lynn/lhwemail.html#4341 -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
