Thanks, yes a schematic would be great. Can I post it to the web please? I'm sure Tony knows the following, included as background. Here's the adapter I used to read the 2564 in a 2764 programmer: 2564 pins?????? 2764 pins 20 (A11)??????? 23 (A11) 23 (A12)??????? 2 (A12) 2+27(CS1+CS2)?? 22 (OE) 1 (Vpp)???????? 28 (Vcc) 22 (PD/PGM)???? 20 (CE) (NC)??????????? 27 (PGM) All other pins connected straight through. The above can't be always used in the reverse direction (eg using a 2764 in a 2564 socket), as CS1 and CS2 may or may not be tied together depending on the circuit. Also programming a 2564 uses a different algorithm to programming a 2764. For example, on a 2764 Vpp can be left at programming voltage of 21V during a verify cycle, whilst on the 2564 Vpp is at 25V for programming and 5V for verifying / reading (I assume the 25C64 is similar but with a lower Vpp). Regards, John ============================================================== Tony Duell ard at p850ug1.demon.co.uk Mon Oct 11 15:29:35 CDT 2010 THanks. I've downloaded it, it unpacks OK. I wondered why the file was larger than ecxpected, but then saw you'd included both hex and binary images. I will probably burn it into a 27C64 (those I have, and my programmer can easily handle them) and make an adapter to use it in the MW4. Then we can see if that gets mine working. I won't be doing this just yet (I've gor various other things to do), but I will let you know how I get on when I do do it. If you are going to disassemble the ROM, do you need schematics of the MW4 hardware? -tony