Re: Testing memory in an ULTRA60

[<rjs%fdy2.demon.co.uk@localhost>]

Volker A. Brandt <vab%bb-c.de@localhost> wrote:
>> > Anyway, according to Volker they must be identical because the machine
>> > would otherwise reject the bank.
>>
>> That's not necessarily true.  Most versions of OBP will read the DIMM SPD
>> information to come up with a common configuration and use that.  DRAM
>> configuration is a complicated mess.  They may even all be the same size,
>> but if even one of them has a different layout of banks it can restrict
>> the use of the entire bank.  What you really want to do is dump the
>> contents of all the SPD data from the DIMMs and compare them, but I don't
>> know how to do that offhand without a debug OBP.  You might want to poke
>> around in the Forth dictionary to see if there's some way to access that,
>> but it's unlikely since it's usually only processed during the config
>> phase.
>
>While I'm sure Eduardo is correct, and all that is theoretically
>possible, I have never seen anything like it in practice, especially
>with those old OBP revs in the U60.  The only really good way would
>be to open up the box and look at the part numbers on the memory
>DIMMs, though.

I have seen what Eduardo describes, which is why I asked whether the
DIMMs were identical not just whether they had the same part numbers.

Robert Swindells