[Coco] [Color Computer] CoCo keyboard

[John]

Hi,

I was wondering if someone could send me a schematic for the CoCo. I 
have a 1981 Motorola Microprocessor Data manual which has a circuit 
of something resembling the Coco. Keith Howell has a lot of good 
information on his web site.

I would like to know how the CoCo ROM scans the keyboard through the 
PIA. I would like to interface a PS/2 keyboard to a PIA in VHDL. I 
know I have discussed this issue in the past. My concern is that the 
PIA is bi-directional, so in theory it should be possible to scan 
the keyboard using Port A as an output and port B as an input or 
vice versa. My concern is that a number of games may bypass the CoCo 
ROM routines and do their own "thing" with the PIA. Bi-directional 
switching in FPGA's is possible ... but just a bit messy. Is there a 
convention for the keyboard ?

Has anyone disassembled the CoCo ROM ?

I would like to use a Compact Flash module for the CoCo. There was a 
discussion on this a few months back. I could either write a Compact 
Flash driver for the Coco which would probably mean patching the ROM 
or simulate a Floppy disk interface with the compact flash.

I assume the CoCo has internal drivers for a floppy disk. I had an 
idea of simulation a Floppy Disk Controller front end while using a 
Compact Flash on the Back end. Does anyone know which FDC the CoCo 
uses ? The SWTPC uses the WD1771, but I think the CoCo uses a 
Motorola chip.

How many bytes / sector does the CoCo use ? OS9 uses 512 byte 
sectors I beleive which is compatible in size with the Compact 
Flash. Flex on the other hand uses 256 byte sectors which is a bit 
more difficult to simulate on a compact flash.

Thanks

John. 




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