[Color Computer] Re: [Coco] New CoCo game demo: Glove.

[Joel Ewy]

James Diffendaffer wrote:
>> ...
>> If I can just figure out what this RGB/Composite stuff is...  Two 
>> different palettes?
>>
>> bye,
>> James McKay.
>>     
>
> Yup.  Sadly the hardware doesn't make colors look the same on both so
> you have to create two different palettes.
> I don't know of any way to detect which output is being used other
> than to ask the user....
>   

    I remember reading some speculation somewhere that one of the unused
pins in the RGB header might originally have been intended to be used to
detect the RGB monitor, perhaps through an unused PIA line.  [Digging
through CoCo 3 service manual...]  Aha.  According to the schematic, pin
10 of the RGB port on the bottom of the CoCo 3 does connect to pin 13
(Port B, bit 3) of  IC4, and it's pulled high with some resistors.  And
the service manual also says on page 10 that bit 3 of $FF22 is "RGB
Monitor Sensing INPUT".  However, the RGB monitor may not actually drive
the line low.  In the manual for the CM-8 it calls pin 10 a No Connect. 
I suppose a ?(PEEK(&HFF22)AND 8) with an RGB monitor plugged in should
yield an answer.  Or something like that.
    What one could do if the monitor sense input is not used by the CM-8
is make a little cable adaptor that would ground pin 10 when the RGB
monitor was plugged in.  You could test the PIA input and conclude that
a (modified) RGB monitor is plugged in if it is low.  If it is high, it
is either a composite monitor or an unmodified RGB.  In that case, ask
the user.


JCE