A1200 Keyboard to PS/2 or other interface..

[psxphill]

The problem is that the A1200 keyboard is passive matrix connected to an microcontroller on the motherboard. That may not be reused easily. And if it fails there's no firmware sources..

I heard the A1000 & A500 keyboard MCUs are going to be decapped.
 
Which would have the benefit of supporting multiple key presses. Although they are 6502 based with alot of onboard IO instead of exposing the data & address bus, so a home made replacement would take a few chips.
 
There isn't going to be much code, so porting it to another MCU probably won't be that hard. Or a replacement could be made using a softcore on an fpga, though the cost of that would probably be higher than using an off the shelf MCU.

[psxphill]

@psxphill, "I heard the A1000 & A500 keyboard MCUs are going to be decapped.", how do you mean?, reading out the binary code?

Yeah, like this: http://decap.mameworld.info
 
It's probably not that hard to actually write from scratch, but running the real code would be much cooler.

[psxphill]

@delshay, Where do you connect the A500 keyboard to the A1200 ?
 
@psxphill, It's likely more work to extract the binary from the obsolete MCU than to make a fresh C implementation which would be better as it can be compiled for any MCU of choice.. As a effective countermeasure to manufactor EOL suprises..

The A500 and A1200 keyboard are the same. The MCU on the A1200 is on the motherboard, while on the A500 it's on a board that is cable tied to the keyboard.
 
The work to decap the MCU is already going to happen. If someone has a sacrificial A1200 then that can be done as well, though it's rather pointless as the A500 MCU is better anyway.
 
If you use something like this:
 
 http://cgi.ebay.co.uk/AT91SAM7S256-ARM7-Development-Board-ARM7TDMI-S-ARM-AT91-/220629726872?cmd=ViewItem&pt=BI_Electrical_Equipment_Tools&hash=item335e8e7698
 
Then you could just grab the source to a 6502 emulator, the MCU dump and spend the afternoon hooking the IO up.
 
It will be less work if wait until someone gets the MCU running in the MESS emulator first.

[psxphill]

@psxphill, Why is the A500 MCU better than the A1200 one ?

The MCU in the A1200 has trouble with multiple keys pressed at the same time. No idea why.