storage key question

VSPC was originally going to be called PCO (personal computing option ... term slightly patterned after tso) ... until somebody pointed out PCO was a term already in use in France.

PCO was going to be something of an entry level TSO ... and somewhat setup as compebreastion for CMS in that market segment (alternative was running vm370 on the bare hardware with CMS for the conversational support ... with guest batch virtual machine).

there was various kinds of internal compebreastion going on ... and the PCO development organization had a couple people that had written a PCO performance simulator. The PCO performance simulator would simulate various kinds of interactive workload ... and then got the corporation to insist that the CMS development group run similar types of (real) workload and compare the performance numbers. This ploy side tracked a significant portion of the CMS development group resources (running real workload benchmarks to be compared against the PCO simulated benchmarks) for several months. For the simulated benchmarks ... the PCO simulator was showing that PCO was two to ten times faster than CMS (real live benchmarks) ... that lasted until they finally got PCO running ... and it turned out PCO was more like 1-10th the performance of CMS (so much for the correctness of the PCO simulator and the people responsible for it).

a big issue with the vm370 strategy was the fixed vm370 kernel size on the small 370s (real 256kbyte machine and the fixed vm370 kernel around 110kbytes). this was significantly alleviated moving into 138-148 timeframe ... where 1mbyte real storage got to be more common. As part of the early ECPS effort for 138-148 ... some early ecps posts

there was even an effort to have vm370 preloaded on every shipped machine (somewhat like lpar is part of shipped machines today The "vm370 preloaded and part of every (at least endicott mid-range) machine" strategy was eventually overruled by corporate people that were constantly claiming vm370 was non-strategic and shouldn't even exist.

misc. past posts mentioning pco and-or vspc:

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