AlphaStation 200 NVRAM Problem

[Maciej W. Rozycki]

On Fri, 22 Apr 2016, Robert Jarratt wrote:

> I am wondering if I have a chance of reviving this system or if it is beyond
> repair (by me)? I can't get anything out of the console port, and I don't
> know if I should expect to be able to get output from there or not. If I
> know that I should expect output on the serial port despite an NVRAM
> self-test failure then I could investigate that further with my breakout box
> (don't have a protocol analyser).

 If all else fails, then perhaps you could try the SROM mini console to 
get further information, or maybe even recover as there are commands there 
to poke at hardware.

 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).

 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.

 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).

 Hope this helps and good luck with system recovery!

  Maciej