15 Oct
2006
15 Oct
'06
5:56 p.m.
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
16 Oct
16 Oct
5:32 p.m.
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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address has been discontinued due a high volume of junk
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20 Oct
20 Oct
10 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
--
If you attempted to send a reply and the original e-mail
address has been discontinued due a high volume of junk
e-mail, then the semi-permanent e-mail address can be
obtained by replacing the four characters preceding the
'at' with the four digits of the current year.
21 Oct
21 Oct
1:42 a.m.
Josh Dersch 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.
A quick google gives 1 meg ram and separate I&D
is needed for 2.11 BSD.
Thanks again,
Josh
.
2:40 a.m.
woodelf wrote:
Josh Dersch wrote:
Interesting -- I got inspired tonight and I spent a few hours with
VTServer getting 2.11BSD installed on the /73, with the 512k ram board
installed -- it seems to run okay, though I haven't done much with it
yet (Only have the root partition copied over, looks like getting the
rest of the tar files installed will be more of a challenge...). Guess
the 1mb ram requirement isn't strictly enforced -- maybe if I get
_really_ crazy, I'll try it with 256k :).
Thanks,
Josh
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.
A quick google gives 1 meg ram and
separate I&D is needed for 2.11 BSD.
> Thanks again,
> Josh
>
> .
> 
1:19 p.m.
Josh Dersch wrote:
woodelf wrote:
VTserver is different from 2.11BSD. VTserver will run in 192K of
memory. The 1MB for 2.11BSD is no joke. It really takes *a lot* of
memory (for a PDP-11) to run.
However, I'm running it on a 4MB 11/70 and it's quite happy! :-)
Josh Dersch wrote:
Interesting -- I got inspired tonight and I spent a few hours with
VTServer getting 2.11BSD installed on the /73, with the 512k ram board
installed -- it seems to run okay, though I haven't done much with it
yet (Only have the root partition copied over, looks like getting the
rest of the tar files installed will be more of a challenge...).
Guess the 1mb ram requirement isn't strictly enforced -- maybe if I
get _really_ crazy, I'll try it with 256k :).
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.
A quick google gives 1 meg ram and
separate I&D is needed for 2.11 BSD.
> Thanks again,
> Josh
>
> .
> Thanks,
Josh
--
TTFN - Guy
3 p.m.
> Interesting -- I got inspired tonight and I spent
a few hours with
> VTServer getting 2.11BSD installed on the /73, with the 512k ram
> board installed -- it seems to run okay, though I haven't done much
> with it yet (Only have the root partition copied over, looks like
> getting the rest of the tar files installed will be more of a
> challenge...). Guess the 1mb ram requirement isn't strictly enforced
> -- maybe if I get _really_ crazy, I'll try it with 256k :).
>
Guy Sotomayor wrote:
VTserver is different from 2.11BSD. VTserver will run
in 192K of
memory. The 1MB for 2.11BSD is no joke. It really takes *a lot* of
memory (for a PDP-11) to run.
However, I'm running it on a 4MB 11/70 and it's quite happy! :-)
No, I'm quite positive that I've booted and run 2.11BSD on my /73 with
only 512k memory, honest :). I can attach the output of the machine
booting if you want proof. Now, as to how _useful_ 2.11BSD will be with
only 512k ram...
Josh
6489
days inactive
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6 comments
4 participants
participants (4)
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bfranchuk＠jetnet.ab.ca -
derschjo＠msu.edu -
ggs＠shiresoft.com -
jhfinedp3k＠compsys.to