bwmott@xxxxxxxxxxxx wrote:
>
> > You know what would be neat if difficult and complex? Bank-switching
> > hardware that works by recognizing the 6502 opcodes as the processor retrieves
> > them, and adjusting the mapping accordingly.
>
> Yeah, but the hardware has to be smart enough to know the difference
> between opcodes and data. That would require it to remain in lock step
> with the 6507 and know about all of the 6507 instructions wouldn't it?
Without the control bus available to the bank-switching circuit it would
seem pretty dang hard.
> One thing I've wondered is if it's possible to overclock the 6507 in
> the 2600. Maybe the 6507 in the 2600 Jr could handle running at the
> same speed as the TIA. Has anyone every tried this?
Probably not 3.58 Mhz, but Kevin Horton once wrote about doing 2 Mhz
with chips straight out of the 2600 (I think, or maybe they came out of
~1 Mhz 8-bit computers...) You could maybe reduce the cycle ratio to 2
color clocks per machine cycle with over-clocking.
How about getting one of those 16 Mhz 65C02 from WDC, cutting out the
6507, and clocking the new design to run at a reverse ratio: 3 machine
cycles for each color clock... and while you're in there re-wiring
things, run a line from the R/W pin on the CPU to the spare ground pin
on the cart port to get one-for-one mapping out of cartridge RAM. A
Turbo2600. That would be fun to code for!
--
mor@xxxxxxx
http://www.crl.com/~mor/
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