The physical components of a computer can be grouped into four categories: the system unit, input devices, output devices, and storage devices. The system unit houses the main computer components including the motherboard, CPU, RAM, expansion cards, and connections for other components. The motherboard serves as the central component that connects the other parts of the computer including storage devices, expansion cards, and buses that allow communication between all components.

1. Computer Hardware
The physical part of a computer

2. Introduction
 The physical parts of a computer are called
hardware. In this chapter, we will examine the
different types of hardware according to four groups:
 The system unit,
 Input devices,
 Output devices,
 Storage devices.

3. The System Unit
All of the main components of a computer

4. Chassis (Case)

5. Power Supply

6. Uninterruptible Power Supply (UPS)

7.  The mainboard (also called the motherboard, or
system board) is the biggest board inside your
system unit. All the main components of your
computer connect to the mainboard. The CPU, BIOS
and chipset are normally situated on your
mainboard along with all the other electronic
components.
 The storage devices, such as the hard disk and DVD
drive, are attached to the mainboard via data cables.
The expansion cards, such as the video card and
RAM modules, are attached to the mainboard via the
PCI and memory slots. The video and sound cards
can be integrated into the mainboard (onboard).
Mainboard

8. Mainboard

9. The ROM-BIOS (Read Only Memory-Basic
Input Output System)
This chip is a special ROM microchip on your
computer’s mainboard. It ensures that the BIOS will
always be available and will not be damaged by disk
failures. It also makes it possible for a computer to
boot itself.

10. The ROM-BIOS (Read Only Memory-Basic
Input Output System)

11. System Buses
Every component in the computer must be able to
communicate with the CPU through the motherboard.
This connection is done via a collection of copper or
gold tracings attached to the motherboard.
These tiny wires are called
buses. Buses carry data and
control messages between
the components.

12. The Bus Arbitration (Chipset)
 The bus arbitration chipset is an integrated circuit on
the motherboard. It controls how the mainboard
buses are used. If two different devices try to use the
same bus at the same time, it can cause a problem.
The bus arbitrator prevents this problem.

13. Expansion Slots
 Expansion slots hold expansion cards (such as a
video card, sound card, or network card) and
connect them to the buses.

14. ATA and ATAPI Interfaces
ATA & SATA
The current SATA standard provides significant benefits
over ATA in terms of convenience, power consumption, and
most importantly, performance.

15. Peripheral Connectors

16. Internal Speaker

17. Central Processing Unit (CPU)
 A central processing unit (CPU) or processor is an
electronic circuit that can execute computer
programs. The CPU is one of the most important
components inside your computer. It is like the brain
of your computer, because it performs all the
computer calculations. CPU speed is measured in
gigahertz (GHz) and has an important effect on the
overall speed of your computer.

18. Memory (RAM)
 RAM (Random Access Memory) is temporary
memory that the computer uses to store applications
and data that are in use, for example, the operating
system, and a word processor or database program.
RAM is called “random access” because any storage
location can be accessed directly. When you create
data such as a letter or a picture, the computer
stores the data in RAM and then copies them to the
hard disk when you save your work.

19. Expansion Cards
 An expansion card (also known as an add-on card,
internal card, or interface adapter) is an electronic
board added in a desktop computer to provide or
expand features not offered by the motherboard.
Expansion cards need device drivers to function
properly.

20. Some Types of Expansion Cards
 Video cards
 Sound cards
 Network cards
 TV tuner cards
 Video processing cards
 Modems