[Coco] MC6847 External Character ROM

[Zippster]

I was just about to comment on that.  The MC6847 set is 128 characters
whether internal or external as far as I can tell.  In the video Juan linked
I would guess the computer is switching into another rom bank for 
chars 128-255.

- Ed

> On Jan 19, 2015, at 2:09 PM, John W. Linville <linville at tuxdriver.com> wrote:
> 
> On Tue, Jan 20, 2015 at 06:06:49AM +1000, Nick Marentes wrote:
>> On 20/01/2015 5:52 AM, John W. Linville wrote:
>>> You'll be limited to one of two 2-color options with these "graphics",
>>> of course.  It could still be interesting, but it looses some luster
>>> when you have to choose between light green & dark green or light
>>> orange and dark orange... ;-)
>>> 
>>> John
>> 
>> That's for characters up to 128. Can the characters 128 to 255 (8 colors
>> block graphics) also not be reprogrammed?
> 
> The colors don't come from the ROM data.  The high bit of the data
> in the RAM is fed back into the VDG to select the semi-graphics mode,
> so the color and the encodings are all internal to the VDG.
> 
>> Even so, hires graphics, even only light and dark green, would make VDG text
>> displays so much nicer... and it only eats 512 bytes!
> 
> It could be cool, yes.  Just not as cool as one might think at first. :-)
> 
> John
> -- 
> John W. Linville		Someday the world will need a hero, and you
> linville at tuxdriver.com			might be all we have.  Be ready.
> 
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