[Coco] CoCo/FPGA board (was Multi-Processor 6809 Computer System)

[Mark McDougall]

On 3/05/2013 8:00 PM, Frank Swygert wrote:

> Could a CoCo replacement FPGA board be designed that wouldn't be too
> expensive? Rather than the cartridge port itself a BUFFERED dual header
> would work.

Definitely. The FPGA on this board is roughly 7 times the size of that on 
the DE1, to give you an idea of why it's expensive. It also has 4x flash 
devices, SRAM and SDRAM, which you don't need all of.

I don't see why you wouldn't just leave the cartridge connector - it has to 
be buffered anyway!?!

> The GIME could be a second FPGA (or would one large one with both the
> 6809 and GIME be more cost effective?).

A single FPGA is definitely more cost effective.

> I think CoCo3 software compatibility is a must, but if you drop a lot of
> the older CoCo2 stuff, like what uses semi-graphics modes and other
> seldom used features, it should be okay. You can only have so much
> backward compatibility! Even the CC3 lost a few CC1/2 programs.

The beauty is that you can have an infinite number of designs to load into 
the FPGA, so there's no reason you can't have 100% Coco1/2 compatibility and 
also Coco3 compatibility. Or you can have a single design that is capable of 
both without too much difficulty.

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"