[Coco] MC6847 External Character ROM

[Juan Castro]

I distinctly remember playing with a ROM that allowed 256 different
characters, not just 128.

Se also: the PC-6001, which has a 6847 and uses an external char ROM out of
the box: https://www.youtube.com/watch?v=bfPtrWETdEQ (At about 10 minutes
15 seconds)

And I thoroughly approve the SRAM idea.


Juan Castro
Enviado do meu Olivetti Programma 101

On Fri, Jan 16, 2015 at 11:42 PM, Zippster <zippster278 at gmail.com> wrote:

> Hi guys,
>
> I’ve got my External Character ROM prototype for the MC6847 working.
> There’s a few pics I put up here if anyone is interested in taking a look.
>
> <
> https://sites.google.com/site/thezippsterzone/home/coco2-projects/mc6847-external-character-rom
> <
> https://sites.google.com/site/thezippsterzone/home/coco2-projects/mc6847-external-character-rom
> >>
>
> It’s just using a font I quickly put together for testing (I need to make
> some good ones).
> The design allows for up to 8 dip-selectable character sets.
>
> If anyone is able to dump the contents of an original Lowerkit ROM (or has
> any other character
> sets) and send it to me that would be great.  Or let me borrow the EPROM
> and I can get
> the code off of it… :-)
>
> Next I’m going to see if I can move all the logic into a CPLD to shrink
> the board size and then
> come up with board layouts for the various CoCo 1 and 2 models I have
> available.
>
> This is proving to be a fun project!
>
> - Ed
>
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