to signal external latches (like the 74LS373) to separate the lower address bytes from data bytes.

during an addition operation. This flag is used exclusively for Binary Coded Decimal (BCD) arithmetic.

Here lies the challenge: You will rarely—if ever—find an official, authorized PowerPoint presentation from the author himself available for free download.

Stack Pointer (SP): A 16-bit register used to point to the memory location called the "Stack." The Flag Register

A 16-bit register that stores the memory address of the next instruction to be executed.