[rescue] Sun 3U Expansion Memory Questions

[Patrick Finnegan]

On Thu, Jul 18, 2019 at 3:57 PM systems_glitch <systems.glitch at gmail.com>
wrote:

> Yep, you called it, it's the old Clearpoint logo. Anyone have information
> on this board? Joe Zatarski suggested I map it out with the logic analyzer
> as he did for his VAX RAM board, but I'd rather not :P
>
>
I'd hook a scope up to the chips, and see if you can find any ones that
have the output "stuck" on or off.

My usual method works better with socketed chips - start pulling some and
see how they map out based on the new parity errors you get.  You could
probaly do this -- cut the DO pin from the chip, see how it maps, and then
solder it back together -- unless you have good tools, I wouldn't try
unsoldering the chip intact.

Assuming you can get to an Open Boot prompt, I'd make some Forth code
read/write patters to the ram, and try to find the error.

Anything you do is probably going to be time consuming, unless you can find
better documentation on the board.

Pat