[Coco] Dragon to CoCo Conversion....

[jdaggett at gate.net]

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