6502.org

Sugarlumps Well thanks BillO and Garth for prompt replies.

I replaced the 6502 mainly to allow me to run TaliForth2 (my main objective) and that is excellent.
I chose the Rockwell part to avoid the potential issues with the WDC and I guess I will stick with that at 4MHz.
It is a very nice system as it is.

I must say, that anyone with an RC6502 build MUST use the Improved PIA Communicator (https://github.com/jblang/pia_communicator) on the Nano. Edit a .forth file in Notepad++ and cut/paste into TeraTerm (0msec char & 20msec line delays).
My motivation for trying to increase the cpu speed was in the main to speed up very slow cut/paste into TeraTerm. It now downloads very rapidly without error
and running Forth at 4MHz is plenty fast enough.

Thanks again all,
Reg

Interesting. There must quite a bit of variability. The same board I tried the R65C02-4 to max out at 5MHz (would not boot @ 6) on was one where I was able to get the W65C02 up to 19MHz. Same RAM and ROM. I have a couple others. I'll give them a test someday as I have a new rev of that board (4-layer) that I want to build up.