[Coco] How much of a CoCo makes it a CoCo?

[Mark McDougall]

On 7/07/2011 8:15 AM, Boisy G. Pitre wrote:

> I think a dream CoCo 3+ would be preserving the exterior (case, keyboard,
> etc), removing the power supply and motherboard, and in its place, have
> an FPGA-based board.  Analog RGB would be replaced with a 15 pin VGA
> connector coming out where the composite audio/video ports are now (no
> composite audio/video support would be warranted.)   The serial I/O jack
> could still be there, as well as the joystick ports, but the cassette
> could go.  The reset and power buttons would remain.  Where the 3-4
> modulator hole is we could put something, and the 3-4 channel switch
> would remain but would serve an entirely different purpose.
>
> And of course, the 40 pin cartridge connector would still be there.

Well this is spooky. Myself and a few colleagues have been toying with this 
idea for a few years now, pretty much *exactly* as you described. We even 
code-named it "coco3+". Hmmm... anyway, still hasn't gotten past the concept 
stage as we have other time commitments atm. The biggest sticking points are 
interfacing to legacy hardware, and also pin-count when including the 
cartridge connector (and also direct-connect to legacy floppy drives as 
there's no real need to do that via a physical disk controller). These make 
it rather expensive!!! :(

Speaking if custom hardware... have you guys seen the NatAmi project?
<http://www.natami.net/hardware.htm>

The C-One was the first (that I know of) purpose-built FPGA-based board for 
(primarily) C64 emulation. It has long-suffered from under-powered silicon 
and IIUC is pretty-much dead-in-the-water, despite an effort to revitalise 
it more recently with an add-on FPGA board.

Minimig, the A500 project, has its own hardware as well.

The MSX computer had the One-Chip-MSX (OCM) hardware, which even came in a 
sexy translucent case, but that's sadly discontinued now. It too, suffered 
from under-powered silicon IMHO, but sold out rather quickly. Not sure why a 
2nd run didn't get off the ground.

Suska, the Atari ST project, has its own board, but I know very little about it.

That's all I'm aware of atm. There are other purpose-built FPGA boards, but 
they're designed for a range of retro emulations, not one target 
specifically. Mike's Replay board from FPGAArcade is one example, MCC another.

Other projects, like the Coco3FPGA, have 'adopted' certain FPGA dev boards 
as their primary platform. There are ports for Minimig, Zet (PC) and others 
for the DE1/DE2, for example, which seems to be the most popular choice.

NatAmi however appears to be the most advanced and ambitious project to 
date. The EP4C40 is larger than the DE2 FPGA, and being Altera silicon I 
would much prefer this board over the Xilinx-based Replay. There's no reason 
the Coco3FPGA couldn't be ported to this hardware eventually, though using 
DDR2 rather than SRAM does introduce some technical hurdles that need to be 
overcome for the Coco.

Regards,

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