Kevin Greene wrote:
Eric Smith wrote:Bryan Parkoff wrote:Do you mean that 6502 / 65C02 CPU chip are limited to 1MHz according to the CPU design?No, they're limited to 1 MHz due to the Apple II design.If you rewire 6502 CPU to 14M crystal osc by modifying timing logic, it might work without accelerator card.Not if you want your Apple II to actually work. The other logic and memory chips in the Apple and on peripheral cards are not fast enough, so nothing would work correctly. But even if the electronics otherwise worked, you wouldn't get proper video, because all the timings would be approximately fourteen times too fast. Your horizontal and vertical sync would be around 220 KHz and840 Hz, rather than around the required frequencies of 15.75 KHz and 60 Hz.And even if all that worked, you'd have to rewrite RWTS and any sound routines.
> Let's say I just upgraded all the components on the motherboard to work > at the faster speed. Assuming that I didn't care about video output > (Any RGB cards work > 1mhz?) or floppy drive access (is this only 5 1/4" > that use timing loops? Would any of the 3.5" drives work? Or the CFFA > works I think) could it work? A few things might work, but not many. Almost every peripheral for the Apple II counts on the timing of the Apple bus and the frequency of the clocks. And, of course, they are designed with logic that doesn't run well at 14MHz. BTW, you *have* to care about the video, since it's the only way to see what an Apple II is doing! RGB cards just change the color coding, not the scan standards that are set by the main board. > I suppose at that point you might as well create another 6502 computer > with the apple ROM. Now you've got it. -michael Music synthesis for 8-bit Apple II's! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it is seriously underused."