Central Processing Unit(CPU) is the main part of any computer system. This unit explains central processing unit and the components inside it. It describes instruction formats and their execution by the control unit. It describes how control unit cycles through fetch, decode and execute operations to carry out program instructions stored in main memory It also discusses the role of registers and buses in programs execution

Lecture Objectives

• Define CPU and components (ALU/CU), Registers, Cache and Internal Buses 
• Define the fuctions of general purpose and special purpose registers 
• Define bus and explain data bus, address bus and control bus 
• Define instructions and its types 
• Exaplains instruction formats 
• Describe instruction cycle (Fech, Decode and Execute). 
• Describe CISC and RISC architecture

Key Points

• Central Processing Unit (CPU) is a single unit that consists of ALU and Control Unit It is the "brain" of a computer 
• Arithmetic Logic Unit (ALU) is the part of the computer where actual processing takes place. 
• Control Unit directs and coordinates thg BctiV1ties of the entire computer system. It controls the working of all the input/output devices, storage devices and the calculations performed by the ALU. 
• A bus is a group of parallel wires used for transmitting binary information from one part computer to another. There are three types of buses, address bus, data bus and control bus. 
• The general types instructions used in computers are data movement, operation. shift companion, branch and input/output instructions Instruction code is a group of bits that tells the computer to perform a specific operation. 
• Control Unit repeatedly cycles through the FETCH, DECODE and EXECUTE steD5 till the last instruction of the program is executed 
• CISC stands for Complex instruction Set Computer that supports a large variety of instructions, which may be as many as three hundred
• RISC stands for Reduced Instruction Set Computer that support very simple Iimited number of instruciton

Referenced Material