BY MANJU Lesson 21 Computer Hardware

System Components A computer system requires many components to do its job: Input: Device to input data so it can be processed. Examples: Keyboard Process: Circuits and programs in order to process the data. Output: Output device to give the result of its processing to the user. Examples: Monitor Storage: Some mechanism for storing data 2

System Components 3

The Motherboard The motherboard is a circuit board inside the microcomputer’s plastic case. It contains the following The central processing unit or CPU Basic controllers Expansion ports and slots Memory 4

Video on CPU 5

The Central Processing Unit The CPU is a tiny silicon chip Brain of a computer system. The system clock controls the speed of the CPU. The rate of the pulse is measured in megahertz (MHz) 1 MHz = 1 million cycle per second 6

Communicating with the CPU Data is represented in a computer in binary format as a series of 1s and 0s. Every 1 or 0 is a bit of information. 7

Communicating with the CPU (cont.) Computers use standardized coding systems (such as ASCII- AMERICAN STANDARD CODE FOR INFORMATION INTERCHANGE) to determine what character or number is represented by what series of binary digits. Data is stored in a series of 8-bit combinations called a byte. Every character, such as a letter, number, or punctuation mark, is a byte created from a unique combination of ones and zeros. 8

The Central Processing Unit (cont.) The CPU has two primary sections: The Arithmetic/Logic Unit (ALU) – Performs arithmetic (+, -, x, /) operations – Performs logical(, =) operations. The Control Unit – Fetch instruction from memory – Decodes instruction to machine language which is 1s and 0s and sends it to ALU 9

The Instruction Cycle and the Execution Cycle in RAM 10

The Machine Cycle Computer Literacy BASICS11 The instruction cycle and one or more execution cycles create a machine cycle. Machine cycles are measured in microseconds.

Basic Controllers A controller is a device that controls the transfer of data from the computer to a peripheral device and vice versa. Controllers are contained on a single chip on the motherboard. 12

Ports are specialized plugs that connect peripheral devices to the computer’s motherboard. 13

Expansion slots are openings on the motherboard where a circuit board or memory chip can be added. Computer Literacy BASICS14

Types of Computer Memory There are two types of memory found on a motherboard: RAM: Random Access Memory ROM: Read-Only Memory Computer Literacy BASICS15 RAM chip

Random Access Memory (RAM) RAM is short-term memory where data is processed while a program is running. Data stored here can be modified as needed. This type of memory loses any data it holds if the computer is shut down. RAM is also called main memory. Computer Literacy BASICS16

Read-Only Memory (ROM) ROM is memory placed on the motherboard by the manufacturer Contains instructions, such as BIOS ROM, that tell the computer how to start itself. This data cannot be modified by application programs. The contents of this memory are not lost when the computer is shut down. 17

Quick Quiz How many primary sections does the CPU contain? Computer Literacy BASICS18

Two 19

Which of the following is the most popular standardized coding system? A. ABCDE B. EXEXCT C. ASCII D. STDRD 20

ASCII 21

Short-term memory on the motherboard is also referred to as _______________. A. RAM B. ROM C. PROM D. None of the above Computer Literacy BASICS22

RAM 23

Execution Cycle of a CPU is measured in 1.Hours 2.minutes 3.milliseconds 4.microseconds 24

microseconds 25

Which is the main memory of the computer? A.RAM B.ROM C.Hard disk D.Floppy disk 26

RAM 27

Full form of CPU is ______________ 1.Common Processor Unit 2.Central Processing Unit 3.Computer Processing Unit 4.Central Peripheral Unit 28

Central Processing Unit 29

1 Byte = _______ bits? 30

1 byte = 8 bits 31

TOPICS FOR NEXT CLASS Input devices. Output devices. Storage devices. 32