[Coco] Cartridge memory - mapping in and out
msmcdoug at iinet.net.au
Tue Oct 30 19:24:47 EDT 2007
Mike Pepe wrote:
> If this were my project, I'd use an "indirect" method to program the
> flash. I'm thinking something like Tony D.'s ubiquitous auto-increment
> circuit he uses in his super floppy controller, ram disk, and eprom
> programmer. You can use a few addresses in the *SCS range to program the
This whole project only came about in the 1st place because I noticed people
talking about EPROM carts on this mailing list and we had spare space on a
panel that had been sitting there for 6 months waiting to be sent out.
My 1st idea was a 'proto' cart, but then I scaled it back to a simple EPROM
cart. Whilst designing that I thought it would be a simple matter to add
flash and have it programmed from the Coco. I put the design out there for
comments, but ultimately I'm guilty of not doing the research myself.
My 2nd incarnation (Coco Flash2) uses a CPLD, but falls short of decoding
all the address lines due to the low pin count. Fortunately, I *think* I
have a solution - one that won't risk the cart or coco at all, and doesn't
rely on manual switching by the user. I'm currently waiting on CPLDs...
Had the CTS# line been driven during a write cycle, then in theory my
designs should have been sufficient. I must admit that I did wonder about
write cycles mapped to ROM, but (rather foolishly) ignored the question.
Well at least I learnt something...
| Mark McDougall | "Electrical Engineers do it
| <http://members.iinet.net.au/~msmcdoug> | with less resistance!"
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