VAXstation 3100-M38 Memory + Ultrix ?

[Michael Kraemer]

hello world,

I have this vintage VS3138 running Ultrix/VAX 4.5.
The machine has these strange memory cards,
base + piggy back unit.
Recently I acquired cards with larger capacity,
at least that's what I thought.
Console (TEST 50) tells me I should have 32MB
(8MB onboard plus the two extra cards),
which looks OK to me.
However, when I boot Ultrix, it tells
me it sees only 20MB.
Is this a known behaviour, or
does it mean one of the memory boards
went belly-up in the mean time ?

I've seen similar behaviour on DECstations,
where certain memory configurations are accepted
by the console, but are rejected by Ultrix.

TIA,
MK

[Bob Koehler]

Post by Michael Kraemer
hello world,
I have this vintage VS3138 running Ultrix/VAX 4.5.

I'll assume you mean VAXStation 3100 Model 38. Shortened forms are
not unique. (Maybe it's a VAXServer?)

Post by Michael Kraemer
The machine has these strange memory cards,
base + piggy back unit.
Recently I acquired cards with larger capacity,
at least that's what I thought.
Console (TEST 50) tells me I should have 32MB
(8MB onboard plus the two extra cards),
which looks OK to me.
However, when I boot Ultrix, it tells
me it sees only 20MB.
Is this a known behaviour, or
does it mean one of the memory boards
went belly-up in the mean time ?

IIRC, in ULTRIX days you may have had to regenerate the kernel to
recognise more memory.

[Michael Kraemer]

Post by Bob Koehler

Post by Michael Kraemer
I have this vintage VS3138 running Ultrix/VAX 4.5.

I'll assume you mean VAXStation 3100 Model 38.

Yes. Sometimes I prefer sloppy language.

Post by Bob Koehler
IIRC, in ULTRIX days you may have had to regenerate the kernel to
recognise more memory.

OK, I'll look into this one, but
I'm not sure if this is generally true for "modern" versions
such as 4.5. At least with DECstations I observed that the
Ultrix boot procedure immediately reported the increase
in available memory after a memory upgrade.
I think I saw a similar effect for the VAXstations,
but there Ultrix maxes out at 20MB.
I find it confusing that the OS reports different numbers
than the console.
A similar effect occurs with DECstations when they are
populated with RAM parts of different capacity (i.e.
mixed 8 and 32MB). I once had a single 32MB part in the
first memory slot and 8MB in the remaining slots.
I was happy the console reported lots of memory,
but Ultrix only took the first 32MB :-(
This behaviour is even mentioned in the Ultrix FAQ,
but no mention of Ultrix on VAX.

[Bob Koehler]

Post by Michael Kraemer
Yes. Sometimes I prefer sloppy language.

Actually, I see it now in the title.