[Coco] MC6847 External Character ROM

[Zippster]

I’d have to design a board that provides access to the IO select signals on
the 74LS138 and both the address and data bus to allow for this,
so all the signals would be there.  The logic would just have to be worked out.

I’m trying to stay away from the cart port signals for the internal mods though.

- Ed

 
> On Jan 23, 2015, at 12:00 AM, RETRO Innovations <go4retro at go4retro.com> wrote:
> 
> On 1/22/2015 11:32 PM, Zippster wrote:
>> Well, I think I’ve found an abundance of unused locations if I’ve read the SAM
>> datasheets, CoCo2 memory map and schematic correctly.  96 unused addresses
>> listed as ‘reserved for future use or special io’ (FF60-FFBF).
>> They don’t seem to be used by either the 74LS783 or 74LS785 SAM versions,
>> so if they do actually light up y7 as they should on the 74LS138 (IC11) I can
>> use them for all kinds of stuff.
> 
> Would it be possible to set one byte as an MMU to remap the char rom (ram) into another slot in the Coco?
> 
> 
> 
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco