This document provides information on basic processing units. It discusses how the processor fetches and executes instructions one at a time by incrementing the program counter. Key registers like the instruction register and program counter are explained. The basic phases of fetching an instruction from memory and executing it are described. Concepts like register transfers, performing arithmetic/logic operations, and fetching data from memory are summarized. Important exam topics related to control units, branch instructions, and multiple bus organizations are highlighted.