6502 is notoriously difficult to target a C compiler to. Limited stack depth, only 3 registers, and I believe some other limitations to the ISA that make hand it hard to target C to it.
cc65 seems to be the only viable one around last I looked. And it doesn't support the 65816, only the 6502. WDC offers their own compiler, but it's not fully open/free.
cc65 seems to be the only viable one around last I looked. And it doesn't support the 65816, only the 6502. WDC offers their own compiler, but it's not fully open/free.