IBM PS/2 P70-386 SIMM needed...+ a couple other things...

From: Lawrence LeMay <lemay_at_cs.umn.edu>
Date: Tue Aug 10 14:25:24 1999

> On 7 Aug 99 at 18:48, Olminkhof wrote:
>
> >
> >
> > >Basically what I meant is banks of two. There's two SIMMS in a bank, with
> > 2
> > >banks, totaling 4 SIMMS.
> > >
> > >If you install three 2 MB SIMMS, instead of getting a 6 MB memory reading,
> > >you'll get a 4 MB reading and a memory error.
> > >
> >
> >
> > Nope.
> >
> > You'll get a memory error until you run the reference disk. If you have an
> > error while running the reference disk then you have the wrong type of
> > simms.
> >
> > It's not until you get to Pentiums that you need 72pin simms in pairs.
> >
> >
> > >///--->>>
> > > -Jason Willgruber
> > >>
> > >>I've never heard of this "sets of 2" stuff on these.
> > >>They use the same simms as the desktop model 70 . . ie with presence
> > >>detect circuitry.
> > >>
> > >>Hans
> > >>
>
> TMK most IBMs (as well as Ataris, Macs and NEXT) require matching simms in
> pairs, and as well presence detect in the case of MCA. There is a hardware hack
> to get around the P.D. on Peter Wendts site. While I have never tried to add a
> single simm physically except to expand the onboard memory of my 8580 to 4m
> from 2 , IIRC all the docs mention this. I would certainly be delighted if
> this were not so. I have an IBM 486 Ambra (non-MCA) which also requires memory
> in pairs but doesn't require PD and a single spare non-IBM 8meg which sits
> unused because of this limitation. I have an 8570 A-21 desktop (25mhz and 387
> co-processor) and other PS2s. There is also a 16 meg max limitation on most of
> the PS2s altho there are workarounds for this I understand.
>
> ciao larry
> lwalker_at_interlog.com
>

I thought that at least one of the PS/2 model 70 motherboard versions came
with 3 simm slots... I dont recall it needing simms in pairs on the
motherboard, though it does use a non-standard, PS/2 style presence
detect.

Does the original poster have a free MCA slot for a ram expansion board?
I have one for a PS/2 model 70, that I assume would work in your system,
assuming you have the reference diskette for your machine.

-Lawrence LeMay
Received on Tue Aug 10 1999 - 14:25:24 BST