* bit0 - CF - Carry Flag
|| Flags are affected by most operations.
BF is not a physical flag implemented in a register. It only appears on the stack when the P register is pushed to or pulled from it.
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| S (Stack Pointer) || 8-bit || Points to the current location in the stack || Stack is located in page 1 ($0100-$01FF), 8-bit S register is offset to this base