[Coco] DS-69 Digisector Dissection (Was: Re: IO ports Re: (no subject))

[Joel Ewy]

Joel Ewy wrote:

I might add that I was able to generate logic equations from the JEDEC
dumps of the GALs, and I still have those files, dated 6/15/1994. 
Doggonne-it, this has re-piqued my interest.  I don't have time for this.

JCE

> 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.

>

> JCE

>   

>> Willard

>>   

>>     

>

>

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