23 Dec
2013
23 Dec
'13
8:28 a.m.
I have a trs-80 model III. It seems to work ok except that some of the characters on the
screen are wrong...the computer works even though some of the characters on the screen are
wrong (and they seem consistently wrong...a "?" always displays as the same bad
character.
Does this sound like video ram? Or something else?
Any troubleshooting info out there?
Thanks.
-Bob
23 Dec
23 Dec
9:24 a.m.
Video RAM would be at the top of my suspects list
Terry (Tez)
On Tue, Dec 24, 2013 at 5:28 AM, Bob Brown <bbrown at harpercollege.edu> wrote:
I have a trs-80 model III. It seems to work ok except
that some of the
characters on the screen are wrong...the computer works even though some of
the characters on the screen are wrong (and they seem consistently
wrong...a "?" always displays as the same bad character.
Does this sound like video ram? Or something else?
Any troubleshooting info out there?
Thanks.
-Bob
11:55 a.m.
I have a trs-80 model III. It seems to work ok except that some of
the characters on the screen are wrong...the computer works even though
some of the characters on the screen are wrong (and they seem
consistently wrong...a "?" always displays as the same bad character.
WHich is? The tirck is to look to see which bits are wrong, and see if
there's a consistent pattern.
Does this sound like video ram? Or something else?
It could be a lot of things. The chracter generator ROM. The logic
between the video RAM and the character generator. But the video RAM
in the M3 s a pair of 2114s, which are known to be an unrelaible type of
IC. Certianly, I;'d suspect the video RAM first.
Any troubleshooting info out there?
I think the service manual or the TrchRaf (I forget which, they cotnain
much the same information) is on archive.org.
-tony
26 Dec
26 Dec
8:55 p.m.
Try removing and reseating chips (carefully) - seems to solve issues with
TRS-80's on occasions
++++++++++
Kevin Parker
++++++++++
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Bob Brown
Sent: Tuesday, 24 December 2013 3:29 AM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: trs-80 model 3 question
I have a trs-80 model III. It seems to work ok except that some of the
characters on the screen are wrong...the computer works even though some of
the characters on the screen are wrong (and they seem consistently wrong...a
"?" always displays as the same bad character.
Does this sound like video ram? Or something else?
Any troubleshooting info out there?
Thanks.
-Bob
4012
days inactive
4016
days old
3 comments
4 participants
participants (4)
-
ard＠p850ug1.demon.co.uk -
bbrown＠harpercollege.edu -
terry＠webweavers.co.nz -
trash80＠internode.on.net