[Coco] CoCo 3 RGB Pinout

Michael Graham mkgraham at gmx.com
Wed Jul 11 21:39:09 EDT 2012

Oh.  Neat!  I wonder why it shows up as not connected on the CM-8 user 
manual then?  It seems like it would have been advantageous to use it.  
I assume since it's pulled up internally, one would simply ground it to 
let the computer know a monitor is attached.


On 7/11/2012 8:09 PM, Rogelio Perea wrote:
> >From what I can remember it was supposed to be a "hardware key" to allow
> the CoCo to detect automatically what type of monitor it had attached to
> it, and set its PALETTE of colors accordingly: TV/Composite or Analog RGB.
> -- RP
> On Wed, Jul 11, 2012 at 5:31 PM, Michael Graham <mkgraham at gmx.com> wrote:
>> I have a question about the CoCo 3 RGB pinout for those of you who might
>> know.  All the pinout sources I've found list pin 10 of the connector as
>> 'no connection', but upon investigation of my CoCo 3 circuit board (and the
>> schematic I found online) it is in fact connected to pin 13 (PB3) of the
>> 68B21, with a pull-up to +5v.  What purpose is this pin actually supposed
>> to serve?
>> Thanks,
>> Michael
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