TRS-80 Model I Computers

From: Rob Ross <robross_at_earthlink.net>
Date: Fri Jan 10 13:11:40 2003

Speaking of Model 1's....

I just bought one (for $45), keyboard/cpu only. It's an original Model 1 (no
keypad) but has had a Level II upgrade. I have two issues with it though.

First, there's a problem with the video. I know the monitor is fine, because
I have another cpu unit (Model 1 Level II) and that one works fine with the
same monitor. But on the new cpu, the video has "issues". It's "out of
focus" and drifts on the monitor. I have to adjust the H-hold and V-hold,
and I can get a relatively stable image, but it's offset to the left of the
screen such that about 10 characters are clipped, for example I can't see
all of the text from the "READY" prompt.

So, how do I go about fixing it? hehe. Ok, big question I guess. Lets assume
I have no previous experience fixing circuit boards, although I did solder
up my share of ICs and logic gates in college. I'm not in a hurry so if I
have to become proficient in electronics to make this happen, I will take
the time, read the books, etc. Anyone got a reading list to get me from
zero-to-McGyvering a circuit board video fix? (I sense a new long-term hobby
starting!)

Second, how do I go about restoring the Level I Basic ROM? It looks like the
original ROMs are not in this machine so I would have to find one or more
likely figure out how to burn an EPROM and all that...so how do I get a hold
of a ROM image for one, are there references that help me do this, etc?

Thanks in advance!

Rob
Received on Fri Jan 10 2003 - 13:11:40 GMT