AlphaStation 200 NVRAM Problem

[Robert Jarratt]

>  Information on using that is however scarce and scattered, you can find
> some here to start: <http://labs.hoffmanlabs.com/node/1286> and then the
> pinout for the serial diagnostic port is included here:
> <http://manx.classiccmp.org/collections/mds-
> 199909/cd1/alpha/pcdsatia.pdf>
> (the boot sequence is also described here, so you'll know that an NVRAM
> failure is reported by DROM code, i.e. before the final SRM or ARC console
> takes over and is able to use the regular serial port).


Indeed, I don't get any output on the standard serial port. 

> 
>  That's a bit cryptic, but knowing that this is a low-level CPU interface
you can
> gather the wiring from this document:
> <http://h18000.www1.hp.com/cpq-
> alphaserver/technology/literature/164lxtrm.pdf>.
> So BSROMCLK is Tx and SROMCDAT is Rx, but as noted here and in the
> discussion in the first reference you need an EIA/TIA 232 driver and
receiver
> (there is power available on the diagnostic port, so you can use it for
the
> circuit), and of course you need to cross the lines wiring them to your
host.
> 

I don't think the SROM diagnostics are going to help much because the
failure is in the DROM sequence, which comes after the SROM.


>  Finally the SROM console command reference is here:
> <http://h18000.www1.hp.com/cpq-
> alphaserver/technology/literature/srommini.pdf>.
> This manual doesn't specifically cover the Avanti, but I'd expect the user
> interface to be similar -- it's a low-level tool close to the CPU after
all.
> 
>  NB on Avanti the 8kB NVRAM is separate from the TOY/NVR chip (which is a
> Benchmarq BQ4285, providing 114B of general storage only).
> 

I had already located the Benchmarq chip and found the spec to be
insufficient for the 8K NVRAM. The problem is, I don't know which chip has
the NVRAM, I have not been able to locate it and the manuals don't tell me.
I hope it isn't one of the ASICs. I have posted a photo of the board here:
http://bit.ly/1qHQnaB in case anyone can id the NVRAM.

If the NVRAM contents are maintained by the battery then there should be a
way to reset the NVRAM contents, but there does not seem to be a way. I
wonder if the NVRAM persists without power? The manual seems to say that the
TOY is battery backed, but makes no mention of the NVRAM needing the
battery.

Regards

Rob