If you have developed on or used your development board in any significant way, I would suggest using either Arlet's core
, or my core
. Arlet's core is constructed in a conventional manner, and it has proven to be easily extended by others on this forum (BigEd and ELectricEyE).
My core is microprogrammed. It uses two block RAMs, one 256x32 and the other 512x32. One block RAM is used for the ALU control and the other is used for implementing the addressing modes and other control functions. I have provided a Windows-compatible microprogram assembler that you can use to easily add additional instructions.
Arlet's core presently implements the behavior of the 6502, and my core provides behavior roughly equivalent to that of the WDC W65C02S microprocessor. My latest release
provides a complete microprocessor implementation of using the core targeted to a Xilinx XC3S50A-4VQG100I Spartan-3A FPGA. I have specifically targeted that part ti see how small an FPGA I can fit the core (and supporting logic) into. I am in the processing of building a demo board with that FPGA, but it will be 4-6 weeks before my parts have arrived and I've assembled and tested the board. (Note: I have some objectives for that board which are not related to simple raw speed, so the M65C02 microprocessor targeted to the board is not intended to run at 100MHz or greater, although the core by itself can be coaxed to synthesize and PAR at that speed or greater in a -5 Spartan-3A FPGA.)
Windfall took the core I posted in March/April of 2012 and added the supporting structures around it and targeted a Terasic DE0 Nano Cyclone III development board
. Perhaps you can download his demo and see if it's compatible with your development board.