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Revision as of 22:14, 8 April 2021 by Jnc (talk | contribs) (Hmm, good question)
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When is a computer not a mainframe?

A not too opinionated discussion around various ideas about what constitutes a "real" mainframe, and what doesn't, might be interesting. As an example, in the DEC world, the PDP-10 family of computers are usually regarded as mainframes (probably excepting the DEC-2020). But IBM people seem to regard it as a minicomputer. That is not to say one definition is more correct than any other. The PDP-8 and 11 are usually regarded as squarely in the mini category even though some of the larger PDP-11s could rival a 10 in some respects. The VAX was often referred to as a "super mini"; maybe later larger models nudged into the mainframe category? Larsbrinkhoff (talk) 19:03, 8 April 2021 (CEST)

Hmmm. I'll have to go away and think about what 'mainframe' means. (And the meaning may have changed a bit over time, to make it a bigger problem.) One definition might include physical size ('it fills a whole room'), but that's less relevant today. Another might talk about what it does (e.g. big online system), and how it was run (e.g. secured machine room with operators). Another might talk about computing power ('the biggest thing smaller than a supercomputer'), and internal characteristics (e.g. duplication for reliability, ability to hot-swap, etc).
It can get fuzzy at the edges, though. E.g. hot-swapping - IIRC old Tandem's could do that, but I think of them as super-minis.
I don't thing even large -11's were anything more than super-minis (although a large one, with a bunch of MK11s, might be borderline). Likewise even the larger VAXen - although maybe the VAX 9000 could count. A VAXCluster of VAX 9000's would be a mainframe, to me.
There's no way a big KL10 system was a minicomputer. Jnc (talk) 22:14, 8 April 2021 (CEST)