Another approach that I have been investigating lately for old Cherry are these PLCC to DIP adapters. It could allow you to just drop in atmega in the original controller spot maybe... if I understand how that works properly.
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That would only work if the pinout are compatible. It would depend on the chips but it seems pretty unlikely that the old controller chip and an atmel chip would share a pinout.
Hows it any different than pulling the controller out and messily slopping in a teensy with wires? Either way you need to do matrix trace to tell the new firmware what is what right? Granted I am not an expert in this topic... but it seems like it should be possible and a much neater solution to just pop something in a dip socket.
Well I don't know the specific adapter you are looking at using. But in general they do not give you the ability to change the pinout.
So for example on a
44 plcc version of an ATMEGA32 pins 5, 17 and 39 are power pins. If that doesn't match the pins on the orginal chip then the new chip won't be powered.
If you were able to customize which pins are interconnected you'd be a lot closer. You'd probably have to solder in a few passive components to get it to run but that probably wouldn't be too bad.
