[Coco] Coco Homebrew ROM Cartridge?

[Phill Harvey-Smith]

Derek wrote:
> Was wondering if it would be possible to get a Homebrew custom coco 
> cartridge working. I know for the Atari home computer and consoles as
>  well as the NES and SNES there are people who have created
> cartridges for these systems with multiple games on each cartridge,
> anywhere from 3 in 1 all the way up to 100 in 1 games on a single
> cartridge. Could you put multiple game roms with a menu on a single
> cartridge?

Yep, I have done that with a large flashrom, and a CPLD to act as an
address latch, first bank of flash had the menu in it, and then further
banks had the cart code. My multi-cart could also handle .cas files
stored in the flash and would load them into RAM and execute them,
additionally it would re-tokenise between Dragon and CoCo depending on
the source cas file, and the machine it was running on.

I *MUST* make this design available at some point, if there's enough 
interest I could put the designs (eagle) and code (6809 for the cart, 
and freepascal for the programs to build the flashrom file) up, but be 
warned that the documentation is minimal :)

> The reason I ask is I just saw the custom made cartridge board 
> advertisement on the coco3.com home page and it got me curious

Not guilty, but a basic bankswitched cart isn't that hard to do, a 
decoder off the address lines and a latch should do it, even simpler if 
you don't need to use it at the same time as disk drives, as you can 
just use P2/SCS to enable the latch at $FF40.

Cheers.

Phill.

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

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