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Re: NVAX page format (Was: NetBSD/vax 512MB support)

On 2023-05-31 20:52, David Brownlee wrote:
On Wed, 31 May 2023 at 16:43, Johnny Billquist <bqt%softjar.se@localhost> wrote:

On 2023-05-31 17:48, David Brownlee wrote:
On Wed, 31 May 2023 at 13:14, Johnny Billquist <bqt%softjar.se@localhost> wrote:

But simh actually only emulates a rather narrow subset of VAXen, and
none based on the NVAX as far as I can remember.

Ahh.. it's just the KA49 in the 4000/90 which was NVAX, not the
earlier M60. My mistake.
That makes it more challenging, though finding someone interested in
implementin in simh could make a good collaborating project...

Well. As far as I know, simh don't emulate any VAX 4000 at all.
It don't go beyond the 3900, if we talk small VAXen.

See https://en.wikipedia.org/wiki/SIMH#Digital_Equipment_Corporation

The list of VAXen is really limited. And mostly really old models.

Well, I think it's safe to say that _all_ VAXen are really old models
by now :),  but simh has made it as far as 1991 with the KA46 & KA48
(VAXstation 4000 M60 & VLC), which is pretty close to the end of the
range, and just leaves NVAX/NVAX+ in terms of MicroVAX/VAXstations

Well, true that they are all "old". But DEC was churning out new VAX models are a very high rate around that time. I had missed that simh had added the 4000/60. But still, no NVAX yet, and I wonder how accurate the existing emulations are. I certainly seem to remember Bob saying that te only one he had confidence of accurate emulation in the past was the 3900. All others were sortof just hacked together by people without a proper reference about how the real machines work.


Oh, and maybe the VAX 10000 could also have more than 512 meg. But those
are the only two series I can think of where it would be reasonable,
since they were the ones that shared the actual bus design and other
hardware with Alpha.

I wonder if anyone ever took out the 21064 and put an NVAX+ back into
any of the upgraded boxes :)

The 7000 and 10000 machines had the CPU on a board. And you could just swap the CPU board, and keep all the rest. I'm sure swapping was done back and forth more than once.

I know that Update had a DEC 7000, which we eventually scrapped. But we kept the boards, since we also have a VAX 7000. Memory and controllers work on both. There was some board (can't remember which) that required different microcode if used in a DEC 7000 compared to a VAX 7000.


Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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