The system case contains and protects the main computer components. It has expansion bays for drives and ports on the front panel. The power supply converts AC to DC power for components. The motherboard connects all components using buses and contains the CPU, memory, chipset and expansion slots. Storage devices like hard drives and optical drives store programs and data. Ports allow connection of peripherals and expansion cards add capabilities.

1. Inside a computer
BY
Ms.MVidya Kalaivani
Assistant Professor
Dept. of Zoology
G.A.C.W

2. System case
• It is a metal box that contains the main components of the computer.
• It protects all of electronic components inside and provides adequate
ventilation to prevent overheating.
• A computer’s case plays a large part in the overall expandability,
protection, cooling and lifetime of the system.

3. Front panel has:
• 3.5 inch drive expansion bays
• 5.25-inch drive expansion bays.
• On/off switch
• Restart switch
• Power on indicator light
• Hard drive activity light
• USB, Speaker, audio port for
connections

4. • Protection:
• A good rigid, well built case can protect the internal components
from dust, vibration, foreign objects, electrical interference.
• Cooling
• The fan is used to cool the power supply as it operations. The heated
air is released out side.

5. Inside
Computing Systems Week 2 - Hardware5
Power Supply
Optical Discs
(CD/DVD/Blu-
Ray)
Hard Disk &
Floppy Disk
Graphics,
sound &
network cards
CPU & fan
Motherboard
RAM

6. Power supply
• A power supply unit(PSU):
• It is the metal box usually found in a
corner of the case.
• It contains power card receptacles
and the cooling fan.
• This unit coverts the alternating
current(AC) line to the low voltage
direct current(DC)
• The power supply range from 160
watts to 700 watts.

7. Mother board
• Mother board is a multi- layered printed circuit board inside a
computer.
• It uses tiny electrical paths(Buses) to connect each components of the
computer together.
• Front side bus(FSB) or system bus is most important bus in the
mother board. It connects the processor to main memory and the
Northbridge chipset.
• The faster the FSB is, the faster the computer can operate.
• The mother board contains:
The CPU, the BIOS ROM chip,, CMOS setup information.

8. Motherboard
Computing Systems Week 2 - Hardware8
CPU Socket
USB
Audio
Keyboard &
Mouse (PS/2)
Expansion
Slots (PCI or
PCI Express)
Expansion Slot
(AGP or PCI
Express)
Disk drive
connectors
Power supply
connector
RAM slots
Serial PortParallel Port

9. Mother board cont……….
• Expansion slots for installing different adapters cards like
video card, sound card, network interface card, modem.
• The socket for the microprocessor determines the kind of
central processing unit(CPU) the mother board uses.
• Chipset: the north Enbridge and south bridge chip set.
• It manages and directs the flow of data between each of the
components.
• The Basic Input/ Output System(BIOS) chip boots the
motherboard, the memory and peripherals are tested this
process is called Power-On Self Test(POST). This is performed
every time the system is turned on.

10. The real time clock chip: to maintains basic settings and the system
time.
• Slots and ports on a mother board:
• Peripheral Component interconnect(PCI)
• Accelerated Graphics Port(AGP)universal Serial Bus
• Memory slot

11. Ports and interfaces
Ports are electrical connections using multiple wires to sent data.
• PS/2 Ports: a standard serial port connecting a mouse or keyboard
to a PC.
• Serial Port: used for serial communication, only 1 bit transmitted
at a time.
• Parallel port: 25 pin connector and is used to connect printers,
computers and other devices.
• SCSI Port: used to attaching disk drives and printers.
• USB port: (universal Serial Bus) used to connect up to 127
peripheral devices such as key board, mouse, joystick etc.

13. • Expansion cards :It is a circuit board that provides
additional capabilities to the computer system.
• Ribbon cables: wide,, flat, insulated cable used to
transfer signals between the drive and the main board.
• Memory chip: internal storage areas in computers
(RAM).
Types: SIMM or DIMM
• SIMM: Single In-Line Memory Module is a small
circuit board that can hold a group of memory chips.
SIMM normally hold nine RAM chips.
• DIMM: Dual In-Line memory module chips have
168- pins in two rows on the each side of the card. It
increases in speed and bandwidth capability

14. • Storage devices: they are machines
that read data and write data onto
a disk.
Hard disk drive(HDD)for read and
write hard disks.
Floppy drive(FDD) for floppy drive.
• Processors or CPU :Holds the key
for carrying out all the processing
and computational work.