[Coco] Coco "Flash2" cartridge progress

[Mark McDougall]

Ty S wrote:

> If I were to take a blind stab in the dark (without knowing anything
> about your design), you could disable interrupts, perform a dummy read
> from one of the addresses you need decoded to get CTS* low, latch this
> signal for the next bus cycle, and perform the write using the latched
> enable signal.

Not bad, close! Programming the flash is a little more complicated than 
simply writing to an address, so the process is a little more involved and 
not quite as efficient - not that it matters because it's not something that 
needs to be done very often.

I was going to implement a mode, set by writing a register, where the *next* 
write (only) was also shadowed by the flash.

Since I have A14 at my disposal, I'll simply use a mode that shadow writes 
to either of two 16KB blocks, until that mode is disabled. I'll still need 
to write some assembler to do the programming (with interrupts disabled) but 
that's the basic theory at least.

Of course, as Mark has hinted, there could be surprises around the corner...

Serves me right for whipping up a board in a few days, with very little 
research into the coco etc, but since it was spare space on a prototype 
panel and time was limited, I bit the bullet. I've already paid for it with 
2 patches so far... :(

> ... and so forth.  Do I win a prize?  :)

Yes! You get your entry fee refunded, minus a small administration fee. 
You'll receive an invoice in the mail for the difference shortly... ;)

Regards,

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