The 6502 is a very constrained CPU. It only has 6 registers, only one of which (PC) is 16 bits. The stack is fixed at addresses 0x0100 to 0x01FF, and the two

The 6502 is a very constrained CPU. It only has 6 registers, only one of which (PC) is 16 bits. The stack is fixed at addresses 0x0100 to 0x01FF, and the two index registers are 8-bits in size. So is the accumulator and the stack register (hence the fixed address for the system stack) and no stack-based addressing modes. You'll have a severe penalty in doing any 16-bit arithmetic. There is no general multiply or divide instructions. I think the architecture is about as hostile to C as you can get and still be popular.