Talk:IBM System/360 Model 85

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Organization

I have two issues with the way the article is currently organized:

IBM System/360 Model 85#Advanced/special features begins with 'The system console is L-shaped: ...', which is certainly worth mentioning but is neither advanced nor special. I'm not sure whether to change the heading or to create a separate section.
The reference to the 360/25 has a redundant mention of the 85 announcement date but no mention of the 25 announcement date. Would 'The Model 85 has both Read-only and Writeable Control Storage[4]:p.14 (it is the second System/360 to have writeable control storage; the IBM System/360 Model 25, announced earlier in the same month as the 360/85, is the first to have writeable control storage.' be better? Shmuel (Seymour J.) Metz Username:Chatul (talk) 15:55, 14 March 2019 (UTC)[reply]

IBM's first commercially available computer with cache memory

As far as I know, it is the first commercially available by anyone. Is it not? Gah4 (talk) 01:54, 17 June 2020 (UTC)[reply]

According to CPU cache#First data cache, it is; unless somebody can find a reliable source for an earlier commercially-available cache, we might as well just say "the first commercially available computer with cache memory". (If somebody does find one, this page and CPU cache will need to be updated.)

(And, yes, CPU cache should perhaps say "instruction and data cache" or something such as that, unless instruction fetch didn't go through the "buffer", to clarify that there wasn't a split cache.) Guy Harris (talk) 04:34, 17 June 2020 (UTC)[reply]

There is a whole IBM Systems Journal article about the cache, but it was a while ago when I read it. I believe that split cache came later, but it is a good question. They did a lot of studies, including using tapes of instruction traces from real programs. Gah4 (talk) 08:12, 17 June 2020 (UTC)[reply]

"Structural aspects of the System/360 Model 85, II - The cache" (Volume 7, Number 1, 1968, so they were calling it a "cache" by that point). They don't explicitly say whether both instruction and data fetches go through the cash, so my guess is that they do.

Note that a processor can have an instruction-only or data-only cache rather than a split cache; the Motorola 68020 had a 256-byte on-chip instruction cache and no on-chip data cache, for example. Guy Harris (talk) 09:26, 17 June 2020 (UTC)[reply]