EPROM emulator for 2732 / 2764 for PC's.
=========================================

This ZIP-file contains an EPROM emulator. I designed it and tested it and it
works very well.

You can freely distribute and copy this zip file, but please don't change
anything. I give no warrenty or anything like that at all. I don't feel
responsible for any damage done to you or your PC (what's worse? :)

Files.
======
        epromemy.ps   : the circuit in postscript format
        epromemu.txt  : this documentation file
        epromemu.exe  : a small up- and download prog
        epromemu.pas  : the TP 5.5 source code
        epromemu.cdr  : CorelDraw! 5.0 format of the circuit

What does it do?
================

You put the described card into your PC, plug the 
EPROM-emulator into this card via a flat cable outside your PC. Run the
program epromemu.exe (the .pas file is also in this archive) and upload files
to, or download the contents from the emulator to a file. After uploading to
the emulator you can unconnect the emulator from the flat cable and pretend
it is a 2732 or 2764.

When it is plugged onto the flat cable or when it is put into a 2732 / 2764
socket the battery will charge. My battery with my type of RAM chip can be out
(living on the battery) for maybe half an hour or so. This depends strongly
on your battery and your RAM chip. Anyway, it's almost always long enough to
transport the emulator from the PC to your EPROM-needing-device.

For the memory chip I used a 8x8 Kbit cache chip from an old 386 motherboard
(needs some current). Due to the fact that this cache chip is very fast there
are no nasty timing problems :) You can buy these for about $5 to $10.

It is quite simple to make it suitable for smaller or even larger EPROM's. 
Just find a suitable memory area in your PC. I used the 8 Kbyte area above 
adress d800:0000 (dip-switches X1101100 ; the most left one is not connected 
when you use 8 bit switches).

There is also an I/O adress. You should make d0 and d1 high just before 
reading or writing the emulator. Afterwards make it 0 again. This is done so 
that the PC doesn't find anything at boot time that looks like a boot-ROM. D0 
is to enable the EPROM; D1 for switching the LED. I used I/O adress $340 
(dip-switches 11010000 ; the upper and lower two bits are not used).
Also notice that you should not load programms like emm386 or himem or any 
programm that uses the area from d800:0000 to 8 Kbyte higher in case of a 
2764.

In fact it is possible to do so (you don't need to put out the card when you
want to use himem and emm386 again, that's what the I/O switch is for). You
could even use the epromemu.exe prog at the same time with himem/emm386 but
you would have to exclude the memory area d8000 to da000 using something like
DEVICE=C:\DOS\EMM386.EXE RAM D=64 /noems x=d800-da00
                                         ===========


Final hint:
===========
My battery's case was the plus pole. My computer case is connected to the
ground. Touch = pats, beng, boem (OK, it just costed me a new band cable ;)

Hope you enjoy this one. For questions you can mail me or so.


Stefan Wieman.


Email                                  : s.wieman@student.utwente.nl
Homepage (with links to more EL-stuff) : http://cal003102.student.utwente.nl

