Central Processing Unit for SS2


Central Processing Unit for SS2
Brief history of the CPU
The fourth generation computers started with the invention of Microprocessor. The Microprocessor contains thousands of ICs.
Ted Hoff produced the first microprocessor in 1971 for Intel.
Definition of the CPU
The Central Processing Unit (CPU) also known as the microchip or the microprocessor (or processor for short) is the electronic circuitry within a computer that carries out the instructions of a computer program. This is the brain or heart of the computer. The main objective of the CPU is to perform mathematical calculations on binary numbers. Most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit (IC) chip. Some computers employ a multi-core processor, which is a single chip containing two or more CPUs called “cores”.
Components of the Central Processing Unit
The central processing unit consists of two parts:
1. Control Units (CU)
2. Arithmetic Logic Unit (ALU)
The Control Unit: The control unit of the CPU contains circuitry that uses electrical signals to direct the entire computer system to carry out, or execute, stored program instructions. Like and orchestra leader, the control unit does not execute program instructions; rather, it directs other parts of the system to do so. The control unit must communicate with both the arithmetic/logic unit and memory.
Functions of the control unit
The control Unit:
i. activates the appropriate circuits necessary for inputs and output devices.
ii. causes the entire computer system to operate in an automatic manner.
iii. directs the system to execute instructions.
iv. helps in communication between the memory and the arithmetic logical unit.
v. aids in the loading of data and instructions residing in the secondary memory to the main memory as required.
The Arithmetic/Logic unit (ALU): The arithmetic/Logic unit contains the electronic circuitry that executes all arithmetic and logical operations. It is also defined as part of the CPU that carries out arithmetic and logic operations on operands in computer
instruction.
Functions of the ALU units
i. The arithmetic and logic unit executes arithmetic and logical operation.
Arithmetic operations include addition, subtraction, multiplication and division.
Logical operations compare numbers, letters and special characters.
ii. Compares operation test for three conditions:
a. Equal to condition in which two values are the same,
b. Less than condition in which one value is smaller than the other,
c. Greater-than condition which one value is larger than the other.