Program Counter

The Program Counter (PC) points to the next instruction byte to fetch. On both the 65c816 and S-SMP it is 16 bits wide. The low byte is called PCL and the high byte is called PCH.

If incremented past FFFFh, it wraps around to zero.^{[E&L, page 34]}

The 6502 had 16-bit absolute addressing but only an 8-bit adder, so in emulation mode branches that cross a page boundary incur a one cycle penalty. 65c816 native mode has no such penalty because the full 16-bit adder is used.