[Coco] [color computer] Just imagining...

[Phill Harvey-Smith]

jdaggett at gate.net wrote:
> Phil 

Phill << Note spelling :)

> The glue logic using the BA/BS/TSC lines should not be that dififcult to 
> recreate. 

Possibly if you where doing a new design from scratch....tracing the 
damn thing when you are working from scans of the (bare) board, is an 
intresting (and as yet incomplete) experience.

>	A second processor with its own rom and ram can beconfigured as 
> an I/O processor or any coprocessor. 

That is true, though the interesting thing with the Beta, is that both 
CPUs shared the same ROM/RAM, the DMA processor just basically sat 
halted or in a loop transfering data.

Though I guess the thing that complicated this case was the MMU 
implemented in LS+a few pals+some static ram. Guess if you where doing 
it now, you could get away with just the major chips a couple of 
CPLDs/FPGAs, and do it in less than 20 chips :) (I'm asuming you don't 
want to bury the whole thing in a big expensive FPGA).

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.