Cache circuit data ram failure

Jul 16 21:10 UTC 1996

I have a Zenith Data Systems 386DX33, to which I added a 387 co-processor.
I also just bought a Cyrix 386->486 upgrade processor in the auction
conference.  Info I have from the Cyrix web site is that this will be fully
compatible with my Zenith motherboard.

the Zenith came with 1 paralell and 2 serial ports, and an extra "Cache
Memory" card which is mounted in the front of the motherboard (as opposed to
the expansion slots which open to the back).  The connector socket is not the
same as the expasion slot sockets.

well, now that I got the Cyrix, my cache has gone ka-flooey!
when I cold boot, I get an error message on POST saying something like
"cache card DATA RAM failure!  Chip: U705" "Press <esc> to continue".

If I <esc> the thing boots up and works, but is s-l-o-w.  If I remove the
cache card I get no error on POST, nor do I if I warm boot (with, or without
the cache card).  I've tried swapping the chips on the cache card (U701 to
U705, and U702, and U708) and I continue to get the error of failure at _chip
U705_.  Since I get no error when the cache card is removed, I am assuming
there is a problem on the cards circuit which relates to socket U705, but I
can find no damage, corrosion, etc, even with close (magnified) inspection.

Q-      Is there a way to test the cache memory card separately?  If so, how.

Q-      Are there other types of cache cards I could use to replace this one?
        What types?  Where would I look?  What might I expect to pay?

Q-      Is this actually a problem on the motherboard, which reads as a cache
        circuit data ram failure?  How can I test/fix that?

        {should I scrap this whole machine and use it for parts, heh?}

please help.

response 2 of 2:

Jul 17 18:20 UTC 1996

I haven't yet installed the new Cyrix chip.  I went by Computer Rennaisance
to see if they might have a new cache card for me.  They said the ZDS's were
very proprietary and, in fact, it might just be something in the BIOS that
prevented it from reading the cache was there...suggested re-setting the bios.
I don't know about that since the error is specific to "Chip U705" and not
a general cache circuit error, but I can be wrong.

I'd sure like to find a way to check the cache card so I'd know, at least,
if I should scrap it or not.