[Coco] [Color Computer] Coco flash cartridge

[Mark McDougall]

Roger Taylor wrote:

> I have a question about the CoCo flash cartridge project.  I don't have 
> the long thread anymore and was wondering if the cartridge will let the 
> CoCo write to an 8K ROM image that is (then and later) treated like a 
> ROM Pak.
> 
> I'm looking at the option of making an 8K programmable ROM Pak like such 
> whether it uses static RAM or Flash memory, etc. but I'm not sure what 
> chips are compatible with this idea.  There's just too many chip speeds 
> and pin configurations to make a quick decision without further research 
> or hearing stories from someone who's accomplished any of this.
> 
> If I make such a pak, it would be as simple as possible, containing 
> nothing but the function of writing to the memory and later having it 
> been seen like a ROM Pak.

This is exactly what the project is designed to do. It will, however, decode 
the entire 16/32KB memory space (using CTS#), as opposed to 8KB, but with 
the Coco3 MMU I believe it is possible to do what you plan.

There are 2 versions of the card - one takes EPROM or flash (up to 512KB) - 
the other takes flash only (up to 4MB). The EPROM version obviously won't 
let you write to the card, but the flash versions will. Flash programming 
algorithms are reasonably simple, consisting of a few 'magic writes' to 
trigger erase or writes.

Regards,

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