[Color Computer] Re: [Coco] Hidden 256-color mode

[Mike Pepe]

James, this is the first message I received in this thread- in addition 
I am only seeing your messages. I'm interested in reading all the 
details here, where/when did this thread start?

-Mike

James Diffendaffer wrote:
> I thought enabling the 256 color mode was difficult because they had
> run out of physical pins on the chip rather than to hide the mode from
> Tandy.  Not releasing the info was because of Tandy for sure.
> 
> Whether or not the 256 color mode is still in the chip probably
> depends on a lot of things.  I think there are a lot of reasons that
> support leaving in the mode.
> 
> We know the prototype would have had to support the mode in order for
> an engineer to test it.
> 
> Unless they reworked the prototype to test it without the mode they
> would probably leave it in to avoid potential problems with the die.
> 
> The mode was difficult to access anyway so removing it wasn't required
> unless there was some incentive to do so.  Changing a design or die
> back then wasn't as easy as it is today.
> 
> Given the diagram for the chip I don't think they would save a lot of
> die space by removing it so there wasn't major financial incentive to
> rework the die.
> 
> And with engineers being engineers I'd say they might leave it in no
> matter what Tandy said.  It's not like Tandy was going to test it to
> see if the mode had been removed.  They probably didn't even know how
> to turn it on in the first place.
> 
> As for how the mode works/worked...
> It would be great if it were a user configurable palette but it would
> require additional hardware to store the palette and handle setup. 
> That increases complexity and size of the die so I don't think it's
> likely.
> 
> However if each byte had the color info built in then the hardware
> just bypasses some of the existing hardware when in the 256 color mode
> and passes on the info dirrectly.  That certainly looks like a "hey,
> we could throw in a 256 color mode by doing this" type of hack and
> engineer might come up with.  It reminds me of the half bright mode on
> the Amiga.  It was there but only a handfull of programs used it.
> 
> The possibilies I see are:
> yyyyyrgb - 8 colors with 32 levels of intensity
> yyrrggbb - 64 colors with 4 levels of intensity
> 
> I think the last one makes the most sense and would be most usefull
> for games.  It still works within the 64 color palette of the CoCo but
> with intensity.
> 
> 
> 
> 
> 
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