[Coco] CoCo 3 FPGA?

[Mark McDougall]

Mike Pepe wrote:

> If we're making a whole new architecture, adding a blitter or a real DMA 
> controller wouldn't be out of the question. That would offload at least 
> some of the video chores from the CPU.

Even then, you're somewhat limited by the system speed. First of all, your 
DMA/blitter cycles must be interleaved with the system clock, which would be 
necessarily derived from the video clock. And keep in mind that even the 
next-gen computers (eg.Amiga) didn't have 16-bit colour. Secondly, whilst 
you can offload the pure grunt-work of shifting blocks around for scrolling 
or blitting large chunks, say textures, to portions of the display, more 
data on-screen generally means more management work for the CPU as well, 
unless you're going to limit yourself to the current resolution.

> My personal opinion though would be to limit it to 15/16 bit color. At 
> least those pixels would fit in one 16 bit register nicely. :)

If you're talking 16-bit _palette_ then sure, no reason why an FPGA coco 
can't have 30-bit colour (the DE2 FPGA board has a 30-bit video DAC for 
example). Large palettes are practically _free_ on an FPGA...

Regards,

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