Re: [ProgSoc] What to do with the SparcCenter2000E...

[Telford <telford@nospam.progsoc.uts.edu.au>]

> > Hang on, I thought you tried one of 'em... twice.  Maybe you can
> > give it a shot with the other board the next time you're around to
> > work on the thing... unless you've done that already.
> 
> i didnt see wether Tel switched em..

Guess I didn't, swithed them today and it came good
also seems like the CPU board is different, this one has
more memory and a pair of CPUs (someone switch that too?)

> >> The error either means that the JTAG system was not working at all
> >> or that it did run the JTAG test and some connection somewhere came
> >> out wrong.
> 
> JTAG ports are pretty low level, i doubt the JTAG port was failing on
> both chips at once. more likely that it didnt find what it was looking
> for. its just a convenient way to implement a POST.

JTAG forms a continuous loop through all the chips, one failure
can disrupt the whole loop.

> >> There is a facility for an external JTAG connector to allow you to
> >> scan all the chips and all the circuits through a PC with a
> >> suitable port.  However, although the JTAG commands are well
> >> documented, the bit patterns that you get back don't mean much
> >> unless you know what all circuit connections in the machine. No
> >> doubt Sun has diagnosis software somewhere that already has
> >> complete bit patterns and can isolate the bad connection very
> >> rapidly. Also no doubt we are not going to get hold of such a
> >> thing.
> 
> You'd probably have to make one by hand, and good luck getting it to
> run at bus speed (50MHz).

There are JTAG cards available for PCs, also the JTAG inludes a clock
line so (in theory) the person driving the bus gets to choose how
fast they clock it (unless you want to do real-time testing).

> Also you'd have to write the software for
> it, and you'd need the specs on the JTAG port on the processor and the
> specs of the bus so you can interpret the results.

This is the hard bit, fortunately it is working at the moment
so we can hold off on the diag for the moment.

-- 
S1G: 14766273 seconds remaining			- Tel
-
You are subscribed to the progsoc mailing list. To unsubscribe, send a
message containing "unsubscribe" to progsoc-request@nospam.progsoc.uts.edu.au.
If you are having trouble, ask owner-progsoc@nospam.progsoc.uts.edu.au for help.