Hi guys,
These come up on eBay every so often, but they are untested or I miss them. Does anyone have any spares of this old chip? I've got an old Apple II that I'd like to use the regular keyboard instead of the PS/2. 
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Pete Rittwage
Wanted: MM5740AA/E Keyboard Encoder Chip
May 1, 2012 - 1:21pm
#1
Wanted: MM5740AA/E Keyboard Encoder Chip
http://www.brielcomputers.com/wordpress/?cat=23
Thats what you want then
That will fix a bad one if you have it and also allow for the use of ps/2.
Only if you have the daughter board version of the keyboard. If you have the MM5740AA/E you most likely don't.
Mine is the early revision keyboard with no daughterboard... Mike has mentioned making some headway with replaceing the MM5740 with new tech, but nothing yet.
One could map a MM5740 pinout to an AVR ATMEGA16 with some socket stacking and rewiring. Then you'd have to write the code to scan the keyboard and map to ASCII. It's not rocket science, but it would take a few weekends of heads down work to get a prototype working. Time I don't have. littlediode.com seems to have MM5740/AAE in stock from time to time.
http://www.willegal.net/blog/?p=2567
Regards,
Mike W.