[Coco] VCC Color question on RGB and Composite emulation

Robert Gault robert.gault at att.net
Sat Apr 6 23:01:30 EDT 2013


Bill Pierce wrote:
>
> Hi Guys,
> I usually run the VCC emulator in RGB mode as my Coco 3 is hooked to a CM-8 RGB monitor and I can test software on both Vcc and the Coco.
> While in NitrOS-9 on VCC, if I switch to Composite emulation, the colors are much different than RGB mode. How close are these colors to a real composite output on a Coco 3 with a composite monitor or TV?
> In developing my software, DW4Man & Sound Chaser, I want to set a color palette to get the same color in composite mode as I get in RGB mode, so I need to know if what I'm seeing is accurate so I can adjust the palettes. The RBG emulation is almost dead on.
> I have 3 or 4 color charts and palette number sets that are supposed to match the two modes, but I just need to know about VCC's composite accuracy
>
> Thanks,
> Bill P.
>

Bill,

You would expect the colors to change when you tell VCC to switch between CMP 
and RGB. What you need to check is what happens after switching VCC and you then 
tell either Basic or OS-9 to also switch color sets.

The command in OS-9 is
montype c
or
montype r
to switch the color set.

I find that the colors in MESS for either mode are quite accurate. So you can 
run VCC and MESS to compare them against each other. You can also take screen 
captures of VCC in each mode after issuing the montype command to compare those 
results.

For a more precise comparison of screen mode colors, you will need to state 
explicitly which colors you want compared giving us the 6-bit palette values. 
Then these can be set on a real Coco3 and displayed on both RGB and CMP 
monitors. Pictures could be taken of the screens and compared.
That still leaves the issue of incorrectly set monitors, monitor differences, or 
digital camera color issues.

Robert




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