re:cache
On 4 Sep 1998, Ian Willmott wrote:
> In message "cache", wojtek@dracula.gda.osk.pl writes:
>
> > I've just repaired my mainboard. Everything is working (all soft), but
> > my cache is not detected.
> >
> > In instruction (AXPpci33 OEM Design Guide,PS format), they show's how to
> > install
> > cache:
> >
> > SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
> > CCCCCCCCCCCCCCCCCCCCCCCCCCCCCC (1) C-contacts, S-socket
> > SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
> > CCCCCCCCCCCCCCCCCCCCCCCCCCCCCC (2)
> > SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
> > SSSSSSSSSSSSSSSSSSSSSSSSSS
> > SSSSSSSSSSSSSSSSSSSSSSSSSS
> > SSSSSSSSSSSSSSSSSSSSSSSSSS
> > SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
> > CCCCCCCCCCCCCCCCCCCCCCCCCCCCCC (3)
> > SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
> >
> > It's written, that 32kx8 chips (256KB cache) should be installed
> > in contacts 2+3,and 128kx8 chips (1MB cache) in contacts 1+3,
> > and it's shown that they are longer and wider than 256KB chips.
> >
> > Mine is only longer, but not wider, so i cannot put it in 1+3 contacts
> > without pin deformations.
> >
> > Should i do it, or it is not the reason why my cache doesn't work
>
> My apologies for not responding to this sooner.
>
> It is the reason your cache doesn't work. I had exactly the same
> problem. The situation seems to be as follows.
>
> The AXPpci33 was apparently designed with the assumption that 128Kx8
> cache chips would always be 400mil wide. It seems that these are now
> being phased out in favour of the 300mil package. Pins 31 and 32 of the
> 300mil socket on the AXPpci33 are not connected to anything, and pin 30
> has a different function on the 32-pin 128Kx8 chip than the
> corresponding pin 28 on the 28-pin 32Kx8 chip. All the other common pins
> have the same function on both parts, and the 300mil and 400mil socket
> holes are connected together (I verified this with an ohmmeter).
>
> Therefore, what you need to do is bend pins 30, 31, and 32 on the 300mil
> chip so that they go in the 400mil socket. If you bend them at the right
> angle, they should still be long enough to make good electrical contact.
> I was able to get a good fit mechanically; I haven't yet powered up the
> board to see if it works. I can't see any reason why it wouldn't. If you
> want to verify my analysis, you can get PDF spec sheets (with pinouts)
> for the 32Kx8 and 128Kx8 SRAMS here:
>
> http://www.alsc.com/product/prod-index.html
>
> See the AS7C256 and AS7C1024 parts. By the way, if anybody needs more
> cache chips, these ones are really cheap, and the spec sheets include a
> list of distributors.
>
> I hope this helps.
OK, i've already got this info, now all works
Thanks
>
>
> Ian Willmott
> Northern Telecom
> Ottawa Ontario Canada
> willmott@nortel.ca.nospam.org (remove everything after 'ca' to reply)
>
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