http://www.e-basteln.de/computing/65f02/65f02/ The 100 MHz 6502 The 6502 was the CPU in my first computer (an Apple II plus), as well as many other popular home computers of the late 1970s and 80s. It lived on well into the 1990s in game consoles and chess computers, mostly in its updated “65C02” CMOS version. Here’s a re-implementation of the 65C02 in an FPGA, in a pin-compatible format that lets you upgrade those old computers and games to 100 MHz clock rate! Supported host systems Chess computers We have focused on Mephisto chess computers first, since these are at the center of Roland’s collector’s interest. But many others are on the wishlist, including Fidelity (Elite A/S Budapest and Glasgow, Prestige, Avantgarde), Novag (Super Constellation, Super Expert C), SciSys (Turbostar), … Mephisto MM II and B&P Mephisto MM IV, MM V, Rebel Portoroz (MM X) Mephisto Polgar Mephisto Milano and Nigel Short Mephisto Rebell 5.0 Novag Constellation Forte A/B Chafitz ARB (various Sargon versions) and MGS Microcomputers So far, we are supporting the two 6502-based members of the classic 1977 “Trinity” of home computers – the Apple II and the Commodore PET series. It may be possible and worthwhile to also support some slightly later machines: The Acorn BBC Micro, Atari 400 and 800, and maybe the Commodore C64 come to mind. I don’t have any of these computers though. Please contact me if you are interested to help with an adaptation of the 65F02! Apple II, including the II plus and europlus, and presumably the //e. Quite a bit of hardware and software trickery by Steve Wozniak, and the older models do not support a real 65C02 – but the 65F02 is a bit more generous in its bus timing and works nicely. The Disk II floppy drive works nicely under DOS 3.3; support for the language card is under development. Commodore PET/CBM up to 8032. A very clean and “by the book” design. The same memory map should work for all models from the PET 2001, the 3000 and 4000 series, and the 8000 series up to the 8032. (But excluding the 8096 and beyond, which require memory bank switching.) So far we have tested this on the 8032 only; the 8050 floppy drive works. A caveat is in order here. The home computers, with their flexibility and expandability on both the hardware and software side, are bound to encounter limitations and incompatibilities: Memory expansion boards and bank switching need to be known to and emulated by the 65F02; and since the 65F02 only has 64 kByte of RAM on board, it cannot fully accelerate the extended memory. Also, while the 65F02 makes an effort to detect the access to time-critical peripheral devices, and switch back to the original slow speed temporarily, there will probably be incompatible software or add-on hardware. And finally, some software you simply don’t want to be accelerated – try an action video game at 100 MHz to understand that concern… The 65F02 supports an optional hardware switch to disable the acceleration. This way, one can still select between accelerated operation and original speed before one starts the host computer. In non-accelerated mode, the 65F02 should be fully compatible with any software or add-on hardware. (Well; unless the software uses undocumented 6502 opcodes…