> Does this still apply to chips made after CSG/MOS went out of business? > Was anyone still second sourcing 6502 by then? I was under the impression that everyone had switched to CMOS designs. > Also, I have doubts about the later 6502 still being NMOS. > It's possible. The 6xxx CSG/MOS chips are supposed to be NMOS, 7xxx HMOS-I & 8xxx HMOS-II, but they have been known to lie (I think the later 6526 were HMOS-II). Conventiently that covers the c64/plus4/c128, so as long as the undocumented opcodes are stable across all three then they are safe to use no matter what process the chip was made with. I doubt MOS/CSG made a huge number of 6502's though, they normally had better uses for their fab. Although they had time to produce the HMOS-II 8501 in 1988 (maybe someone at MOS/CSG loved his plus4, but the CPU broke). Message was sent through the cbm-hackers mailing listReceived on 2017-11-15 14:03:28
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