Help wanted in dumping EPROMs - test-drb@ccmp.vtda.org

5 Oct 1999

Yes indeed!  The data sheets for the two parts will answer all the
questions.  All one has to do is to stay awake.  I wouldn't make such a
statement if I didn't know of instances where one has gone to sleep . . .
that's one who shall remain nameless . . .

Dick

-----Original Message-----
From: Tony Duell &lt;ard(a)p850ug1.demon.co.uk&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Tuesday, October 05, 1999 3:18 PM
Subject: Re: Help wanted in dumping EPROMs

...
 >
> This particular case might be just a bit more involved, since pin numbers
> are more difficult for the unititiated to track between the 44-pin PLCC and
...
   the 40-pin
DIP.  However, it really doesn't require one be a rocket 
Hmm... A good data sheet will show the pin numbering and positions for
the PLCC device.

[..]

  In fact, I'd recommend one attempt to do this
via the EPP port. 
It's not much harder (if at all) to use the plain old standard parallel port.
...

The best way to think of an IBM printer port is that it's 12 TTL outputs
and 5 TTL inputs that you can do what you like with. Use a 74157 (or
similar) to multiplex the 8 EPROM data lines onto 4 of the inputs (control
the mux with one of the outputs). Use 8-bit latches (3 would be enough) to
latch 8 of the outputs (might as well make it the standard 'data' lines),
using other outputs to select them. Use the 24 lines you get by doing that
to address the EPROM, and read the data back in via the mux.

-tony