20 Oct
2006
20 Oct
'06
7 p.m.
Jerome H. Fine wrote:
Thanks for the suggestion, but my (eventual) goal is to get 2.11BSD
running on the /73, so I'll probably need more than 256k of memory
working. I have a 512k board I could steal from my MicroVax I (in fact,
I may just do that for the time being...), but I'd really like to repair
the board I have at some point.
Thanks again,
Josh
Josh Dersch
wrote:
I have a MicroPDP 11/73 I'm trying to get
running again; it has a
single M7551-AP memory board (1MB) which appears to have a stuck bit;
the startup memory test fails with:
Expected Data = 125252
Bad Data = 125253
Address = 01400010
Any ideas how to determine which RAM chip needs to be replaced based
on the failing address?
Thanks,
Josh
Jerome Fine replies:
I don't have an installation guide, but I suspect that
it might be possible to reduce the available memory
until you are able to replace the stuck bit.
Based on the bad memory address, I think that the first
256 KBytes of memory are OK. If you set the end address
jumpers at 256 KBytes, then the start-up diagnostic should
ignore the rest of the memory. If you are able to get by
on 256 KBytes of memory for a while, that might solve the
problem for the moment.
Sincerely yours,
Jerome Fine
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