Subject: Re: [stella] Formats (64K Flat Model??) From: Greg Troutman <mor@xxxxxxx> Date: Tue, 05 May 1998 08:21:02 -0700 |
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/ -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/stella.html
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