On Mon, Nov 14, 2022 at 5:12 PM Paul Ruizendaal <pnr@planet.nl> wrote:

Following on from the exchange on TUHS about DG-UX, it would seem to me that the (Unix) unified cache was invented at least three times for Unix:

Not to quibble too much, but s/cache/memory/ I think is a fairer way of saying that.

- John Reiser at AT&T
- At Sun
- At DG

- At CMU (Mach)

The interesting thing again, is that while they while all of these implementations seem to have been technologically 'better' - only Mach lived on from the original developers. And in the case of Mach, by the time it was mainstream (macOS) the original implementation had been replaced a few times - so while the concepts are there, I don't think much of the Original CMU code is left in XNU/Darwin [or for that matter in the OSF flavors -- Tru64 rewrote it but it died and the OSF/RI kernel never went anywhere either].

As I said, the lesson to TUHS -- as much as I'm a techie and I am interested in the 'proper' way of doing things ... "good enough" is often what rules.

It's too bad none of the good memory implementations made it into >>systems<< that lasted.

Clem