[Coco] Re: [Color Computer] CoCo keyboard

[jimcox at miba51.com]

Do you have a URL for Keith Howell?  I Googled the name 
and came up with a site that looks like the you were 
referring, but would like to make sure.  Thanks!

Jim

On Fri, 16 Jul 2004 06:41:01 -0000
  "John" <John0457 at hotmail.com> wrote:
>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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