[Coco] Dragon to CoCo Conversion....

jdaggett at gate.net jdaggett at gate.net
Thu Jan 18 13:41:17 EST 2007


On 18 Jan 2007 at 17:18, Torsten Dittel wrote:

> > Or even redo the older circuit that uses a MC68HC11E2 to convert PC
> > PS2 scan codes to COCO keysrtoke values.  Since the MC68HC11E2 is
> > discontinued, that makes that a bit more difficult.
> 
> I have a bunch of MIT MiniBoards here with the E2 (2KB EEPROM). Do you
> have the circuit / the 6811 source code?
> 
> AFAIR for unknown reasons some older software changes the PIAs' I/O
> directions (input becomes output and v.v.) of the keyboard matrix
> (AFAIR it was even possible to "short circuit" the older PIAs by
> programming both as an output (one HI and one LOW) and pressing keys
> which damaged the output drivers. This was only noticed later if the
> software changed I/O directions the way described above. I guess
> Motorola changed the design later for protection). How could a circuit
> using the 6811 handle this PIA programming?
> 
> Regards,
> Torsten
***********

here is the link to Dana Peters AT2COCO files

ftp://os9archive.rtsi.com/OS9/OS9_6X09/HARDWARE/AT2COCO.ZIP

In addition to the MC68HC11E2 not being readily available the MT8808 may also 
be hard to find. The source is not included but with some work the 1500+ bytes of 
code could be disassembled/reassembled and used in any HC11 processor.  

The crosspoint switch could be done in a CPLD or t here are probably some other 
replacements that could be adapted. 


james





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