[Coco] IO ports Re: (no subject)

Joel Ewy jcewy at swbell.net
Sat Nov 17 10:58:11 EST 2007

Willard Goosey wrote:
>> Date: Fri, 16 Nov 2007 21:01:32 -0600
>> From: Joel Ewy <jcewy at swbell.net>
>> The DS-69[B] Digisector video digitizer contains a 68[B]21 PIA starting
>> at FF70.  
> Hey, cool.  More stuff for the list!  Maybe sometime soon I can update
> my IO list.
I've always been fascinated by this darn thing (the DS-69) and have done
a little work in the direction of reverse-engineering it.  Back in the
day I had the idea of cooking up some software that would allow one to
digitize in OS-9.  I drew out a partial schematic at one time (the
double-sided board is translucent), and IIRC, the socketed GALs didn't
have their security fuses blown, so into the programmer they went for a
good reading.  More recently I disassembled the little ML program that's
supposed to allow you to digitize from BASIC programs.  But I ran into a
rather mysterious chunk of code, which I posted on this list.  I had
never really used the example BASIC programs, but when I tried out the
one that purports to digitize in 64 levels of gray, I got garbled
results.  I now believe that The Micro Works distributed buggy code.  So
now I may need to disassemble the much larger, more complicated C-See
program rather than the simple subroutine, if I want to figure out how
this thing really works.

> Willard

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