[Coco] Coco proto board

[Phill Harvey-Smith]

Mark McDougall wrote:
> jdaggett at gate.net wrote:
>> Correct a 44 pin CPLD just does not offer enough pinouts. A 80pin QFP 
>> might be a better alternative. 
> 
> Yeah, I've come to the conclusion that 44 pins is pretty useless. It 
> could decode GPIO vs ROM and provide a bank switch for larger ROMs but 
> not a lot else... :(

Yep I have designed a board that does this, allows you to burn a whole 
bunch of carts (or cassette images) to a big flash rom and then select 
from a menu at boot time.

> The next size up for Altera MAX3000 is 100 pin... not much fun to 
> assemble by hand.

Well if you are not wedded to Altera, Xilinx do 84pin PLCC versions of 
the XC9572 and 95108, both of which are also 5V, with these you have 
enough lines to completely decode any address, which means that you can 
put RAM in the $C000 reigon, you'd of course need to use DSD to disable 
the onboard device selection too, and of course this should only be used 
in map type 0 :)

> This was intending as a quick 2-day PCB to round out the panel and 
> perhaps pay for the panel... may not be feasible/useful after all...

Yeah projects have a habit of being like this :)

Cheers.

Phill.

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

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