13 Aug
2015
13 Aug
'15
9:53 a.m.
Hi List,
So a good friend of mine recently resurrected his childhood 286 Wang
PC260 after I suggested he replace the keyboard controller. In the 14 or
so years it's been unused, it has developed a memory fault in one of the
conventional memory banks. The memory is soldered to the board so we're
looking for anything that might assist in tracking down the dud memory IC.
He can get it to boot if the memory size is set to 256kB, so I'm
guessing the second 256kB bank is bad. Is there software that exists
that can identify individual dead or faulty memory IC's, or at least the
corresponding bit(s) which may not be working?
According to Dr. Google, this machine was built by Tandy for Wang.
Perhaps there's a Tandy diagnostic disk that'll work with it, or better
yet a Wang diagnostic disk.
(I'm wondering if this question has been asked/answered before too)
Cheers,
Alexis.
13 Aug
13 Aug
4:40 p.m.
If you can write your own code, usually a simple write and read
sequence will find a dead RAM. Just write 0xFF to a location
and expect to read it back and then 0 and read it back.
You write it so that it will stop at the bad RAM location and
continually loop that location.
Probing with a scope on the chip enables will usually find the
byte that is failing. Then just look at the data pins to see which
chip does not match the others.
It helps to have a two channel scope so one can trigger on the
enable while the other looks at the data.
This is not a high quality manufacture type test but most RAMs
fail completely, making such a test useful.
Dwight
To: cctalk at classiccmp.org
From: thrashbarg at kaput.homeunix.org
Subject: Wang PC260 memory fault
Date: Thu, 13 Aug 2015 17:23:17 +0930
Hi List,
So a good friend of mine recently resurrected his childhood 286 Wang
PC260 after I suggested he replace the keyboard controller. In the 14 or
so years it's been unused, it has developed a memory fault in one of the
conventional memory banks. The memory is soldered to the board so we're
looking for anything that might assist in tracking down the dud memory IC.
He can get it to boot if the memory size is set to 256kB, so I'm
guessing the second 256kB bank is bad. Is there software that exists
that can identify individual dead or faulty memory IC's, or at least the
corresponding bit(s) which may not be working?
According to Dr. Google, this machine was built by Tandy for Wang.
Perhaps there's a Tandy diagnostic disk that'll work with it, or better
yet a Wang diagnostic disk.
(I'm wondering if this question has been asked/answered before too)
Cheers,
Alexis.
5:24 p.m.
On 08/13/2015 09:40 AM, dwight wrote:
If you can write your own code, usually a simple write
and read
sequence will find a dead RAM.
Memtest 86 ought to run on that machine. (Might
have to
find a very old archived version, but any version that will
boot from floppy ought to run on it.) Then, you only have
to figure out which row of chips is which bank, and which
column is which bit. Depending on what docs exist, that may
not be real easy. Last resort is to trace wires on the
board to see which chips are wired to which bus lines and
address decoders.
Jon
3565
days inactive
3565
days old
2 comments
3 participants
participants (3)
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dkelvey＠hotmail.com -
elson＠pico-systems.com -
thrashbarg＠kaput.homeunix.org