[Coco] COCO DTV

Mark McDougall msmcdoug at iinet.net.au
Thu Feb 15 23:03:24 EST 2007


Dan Olson wrote:

> Call me crazy, but why create a new FPGA based computer when the
> C-one sounds like it's exactly the same idea?  Can't a CoCo core be
> written for the C-one board, saving re-inventing the wheel?
> Assuming, that is, that things like a cartridge port and joystick
> ports could be added to the design.  Just a thought.

The C-one has its problems.

The main FPGA is an EP1K100. It's not very big. I suspect you won't fit
a Coco 3 in there, let-alone a Coco 4/5!

There's a secondary FPGA, and EP1K30 which is (not surprisingly) about
1/3 the size. AFAIK its job is to bootstrap the main FPGA and act as a
conduit for all the I/O, i.e. PS/2 input and sound, video output. As
such it could be considered as a fixed-function chip. I also understand
the design of it isn't (or at least wasn't) open-source.

Reportedly there are other design problems on the board which limit
functionality in various ways.

Jens was working on a FPGA plug-in daughter-board for it with a
Cyclone-II FPGA but it seems to have gone cold?!? It was connected via
one of two? "PCI" connectors but again a combination of original design
flaws and limited connectivity restricts the usefulness.

It also requires a PC case of course.

In a lot of respects, existing FPGA dev kits are cheaper, smaller and
more powerful than the C-one. They just don't "look" like a PC.

FWIW in an _ideal_ world I think the Coco 4/5 should be packaged like
the 1-chip MSX. Indeed, I think you'd have little problem implementing a
complete Coco 1 in it! It'd be nice if the cartridge connectors were
compatible...

Regards,
Mark



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