Subject: Re: what's this machine check mean?
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-alpha
Date: 04/15/2000 20:59:23
>>> 30->72 pin converters

>> The surface-mount ICs are 14-pin and hence have pin count enough to
>> be address buffers (data buffers are, of course, unnecessary).
> Databuffers are not unecessary, RAM chips give substantial capacitive
> loading!  You have 4x the number of RAM chips compared to typical
> 72pin SIMMs.

Yes - but each *data* line is still connected to only one chip.

>> I can trace many of the etch runs on the adapter, and it certainly
>> looks as though the surface-mount chips are address buffers.
> Or address decoding.

Except there's no address decoding necessary on the adapter.

>> The bad news is, it didn't work: [...]
> Hm, I still would check what ordinary 72 pin chips do.

In what respect?  In any case, it didn't work, so I won't be using
those adapters further on this machine, and I don't have any
significant amount of <=70ns 30-pin memory anyway.

>> The good news is, it apparently didn't fry anything; when I switch
>> back to the 80ns SIMMs, it works as well as it ever did
> If worst come to worst I can maybe find you a 21066/166Mc chip.  Will
> have to do some digging.

It'd probably cost more to get it to me than it would for me to get one
locally. :-)  Besides, I wouldn't worry about it unless the machine
checks continue once I have 70ns or better RAM in there.  80ns is close
enough I could easily believe it will mostly work at 70ns, especially
since the ECC it does can presumably recover from the occasional error.

					der Mouse

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