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
scientist to figure it out. Like many other tasks it requires attention to
detail. The original inquiry came from someone wishing, probably more than
anything else, to read the contents of his EPROMs without risking damaging
them. It's really not likely that will happen so long as power and ground
are connected to the right pins. An additional risk might be that data
outputs might be shorted to one or another of the rails. If one is careful
enough to avoid those bugaboos, reading the things will be no problem.
In fact, I'd recommend one attempt to do this via the EPP port.
BTW . . . If your printer port is situated at the usual 0x378, then an
outputb to 0x37B will generate a write to the data port (same pins as at
0x378) acocmpanied by an "address strobe" as part of the EPP standard
interlocked hardware-handshake. An outportB to 0x37C will generate a "data
strobe" in the same manner, requiring of course, that one interpret these
correctly and respond with the appropriate "wait" pulse on what would
otherwise be the "busy" pin. I'm not "up" on the Pentium instruciton set to
such extent that I can guarantee that if one writes a WORD to the
odd-addressed 0x37B location it will write the bytes to the two sequentially
adjacent locations, but I would anticipate that if one writes a long word
(32-bits) to 0x37C, most EPP hardware will transfer the bytes low==>high in
order, via the data pins, and acocmpany each byte with a data handshake.
That would certainly make it easy to read from a PLCC socket.
Dick
-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Tuesday, October 05, 1999 12:34 PM
Subject: Re: Help wanted in dumping EPROMs
>>
>> An adapter would not be very challenging to hand-wire, sir. You'll never
>> know when you may need it again.
>
>Agreed. For _reading_ EPROMS, all you need to do is match up the pins
>with the same name (I am told that there are rather more problems in
>making _programming_ adapters for PLDs, but that's another story). You
>can make a 'plug' to fit the EPROM programmer ZIF socket using a
>wire-wrap DIL socket (or some pins), and wire it to a PLCC socket. Should
>take well under 1 hour....
>
>-tony
>
Received on Tue Oct 05 1999 - 15:09:48 BST