The document summarizes the key internal and external components of a computer system. It describes the motherboard as the main circuit board that holds the CPU and connects all other components. The CPU processes instructions using RAM for temporary storage and ROM for permanent storage of startup instructions. Other components described are hard drives for long-term storage, expansion cards for additional functions, power supply for electricity, and input/output ports and drives for connecting to other devices and media.

1. SYSTEM UNIT
• Case, Tower, Chassis, Box
 Box-like case containing electronic components used
to process data

2. Inside “The Box”

3. What are all those parts inside my
computer and what do they do???

4. The magical components inside the box..
CPU
Memory
card
Sound
Card
Video
Card
Storage Units
Power
Supply

5. SYSTEM COMPONENTS
Mother Board
• This is where most of the
electronics is located.
• It is the main circuit board inside
the CPU case. It holds the
microprocessor, memory and
other crucial circuits and
components that control the
operation of the Personal
Computer.
• Every device inside or connected
to a Personal Computer finds it's
way to this board.
Motherboard

6. Major Components of a Motherboard
SIMM RAM Bank
Single Inline Memory Module
stores data to be used by the
microprocessor.
ROM BIOS
Basic Input/Output System
stores permanent instructions
that start the computer.
Power Connector
Supplies power to the
motherboard.
16 Bit ISA Slots
Allows expansion of computer
through modem, sound and
video cards.
32 Bit PCI Slots
Allows expansion cards that
can transfer data faster than
ISA slots.
Battery
Provides power
for the system
clock.
Cache RAM
Stores and retrieves information
for the microprocessor at a faster
rate than SIMM RAM so
instructions can be executed faster.
Microprocessor / CPU
Single integrated circuit that
executes the majority
of the instructions
to process
data.

7. Your computer couldn’t work without the motherboard.
It ties everything together! It allows every part of your computer to receive
power and communicate with each other.
Everything that runs the computer or enhances it’s performance is either part of
the motherboard or plugs into one of it’s expansion slots or ports.

8. 8
The Components of a Computer
• Two main components on the motherboard
– Central Processing Unit (CPU)
•Also called a processor
•Carries out instructions
that tell computer what to do
– Memory
•Temporary holding place for data
and instructions

9. SYSTEM COMPONENT CPU/PROCESSOR
• The CPU refers to the microprocessor chip.
• It’s speed is measured in Megahertz (MHZ) (Millions of cycles
per second) or Gigahertz (GHZ) Billions of cycles per second.
• A cycle is the time required for the CPU to execute an
instruction step
• Once information has been sent to a computer by one of the
input devices it’s processed. The computer uses it’s brain to
process the information. The computer’s brain is called the
CPU, or Central Processing Unit.
CPU
(Central Processing Unit)

10. The CPU is also called
the microprocessor.
The word “micro”
means small. Since the
CPU is located on a
small computer chip
about 1 inch square,
that makes sense!

11. CPU/PROCESSOR
CPU controls all the parts of Computer.
The CPU consists of THREE Components:
1. ALU (Arithmetic and Logic Unit): ALU is
a digital electronic circuit that
performs arithmetic and bitwise
logical operations. It is a fundamental building
block of many types of computing circuits. It
has 2 sections –
Arithmetic & Logic Section.

12. CPU/PROCESSOR
2. Control Unit: It directs operation of the
processor. It tells the computer's memory,
arithmetic/logic unit and input and output
devices how to respond to a program's
instructions
3. Memory: It holds the received data from
input devices permanently / temporarily.

13. Types of Memory:
Ram – Random Access Memory
• Ram is a temporary memory used by the
computer to run Active Programs
and store current Data to make it readily available.
• When a computer processes information, it uses
software programs. Each program requires a certain
amount of electronic memory, or RAM (Random
Access Memory) to run correctly.
• The amount of Ram available will determine how
fast a program will run and how many windows can
be open at one time.
• Ram memory is considered Volatile / temporary
because it disappears when the power is turned off.
More RAM, faster the work!

14. Ram – Random Access Memory
• Dynamic RAM (DRAM) DRAM is a classic form of RAM and has since been
replaced by the faster and less expensive SDRAM. DRAM stores data
electrically in a storage cell and refreshes the storage cell every few
milliseconds.
• Extended Data-Out RAM (EDO RAM) EDO RAM is faster than DRAM. EDO
RAM has also been replaced by SDRAM. EDO RAM is an improvement on
DRAM because it has advanced timing features. EDO extends the amount
of time data is stored and has a reduced refresh rate. This alleviates the
CPU and RAM from timing constraints and improves performance.
• Synchronous DRAM (SDRAM) SDRAM replaced DRAM, FPM, and EDO.
SDRAM is an improvement because it synchronizes data transfer between
the CPU and memory. SDRAM allows the CPU to process data while
another process is being queued.

15. Read-Only Memory
• A second kind of computer memory is ROM,
which stands for Read-Only Memory.
• This memory is permanent. The information
there was put there when the computer was
made, this cannot be changed.
• The computer needs the information in it’s ROM
memory in order to function.
• It keeps its contents even in absence of power.
• ROM chips contain programs that start the
computer and perform system diagnostics.

16. Read-Only Memory
• PROM - (programmable read-only memory) is a memory chip on which
data can be written only once. Once a program has been written onto a
PROM, it remains there forever. Unlike main memory, PROMs retain their
contents when the computer is turned off.
• EPROM - (erasable programmable read-only memory) is a special type of
PROM that can be erased by exposing it to ultraviolet light. Once it is erased,
it can be reprogrammed. An EEPROM is similar to a PROM, but requires only
electricity to be erased.
• EEPROM - (electrically erasable programmable read-only memory).
Pronounced e-e-prom, an EEPROM is a special type of PROM that can be
erased by exposing it to an electrical charge. Like other types of PROM,
EEPROM retains its contents even when the power is turned off. Also like
other types of ROM, EEPROM is not as fast as RAM.
A special type of EEPROM, referred to as flash memory or flash EEPROM, can be
rewritten while it is in the computer rather than requiring a special device
called a PROM reader. This is what most of you will have.

17. RAM & ROM
RAM cards will remember what you tell them and can even
change to remember new information. But, when the computer
is turned off, it forgets everything you did! That’s why you
always save your work!
ROM is good at remembering, but cannot change it’s mind. It
holds the information that was built into it!
Remember RAM (Random Access Memory)
and ROM (Read-Only Memory)?

18. Cache Memory
Cache memory, also called CPU memory, is random
access memory (RAM) that a computer microprocessor
can access more quickly than it can access regular RAM.
This memory is typically integrated directly with the CPU
chip or placed on a separate chip that has a separate bus
interconnect with the CPU.

19. SYSTEM COMPONENTS Hard Drive
• The Hard Drive is the magnetic storage device - the
computers main, long term storage.
• All the computer programs and files you create and
save are located here
• It is referred to as non-volatile storage, because it
does not disappear when the power is turned off.
• The size of the Hard Drive is measured in Gigabytes.
(Billions of Bytes).
HDD
(Hard Disk Drive)

20. Inside the Hard Disk Drive case you’ll find
circular disks that are made of steel.
On the disks, there are many tracks, or
cylinders.
An electronic reading device called the
head passes back and forth over the
cylinders, reading information from the
disk or writing to it.
Hard Disk Drives use Magnetic
Recording Techniques. The
magnetic medium can be easily
erased and rewritten and will
“remember” the magnetic flux
patterns stored on it for many
years!

21. Hard Disk Drives can spin at the rate of 7200 or more
rpm’s (Revolutions Per Minute).
That means in one minute, the hard drive spins around
more than 7200 times!

22. RAM VERSUS HARD DRIVE
• If we use the analogy of
a desk: Then the work
we are doing on the
desk top would be using
the RAM and the work
we store in the file
drawers would be on
the HARD DRIVE.

23. BIOS CHIP
A BIOS chip (Basic Input Output
System) is a very important
computer component.
In simple terms, the BIOS chip
wakes up the computer when you
turn it on and reminds it what
parts it has and what they do!

24. Network Interface Card
A NIC card (Network Interface Card)
allows your computer to talk to
other computers!
A cable called Cat5 is plugged into
the NIC card and your computer can
then be attached to a network and
be on the internet!
Used to connect to high speed
internet access e.g. Cable or DSL
lines ((Digital Subscriber Line).

25. Outside “The Box”

26. CD / DVD Drive
Power Button
Restart Button
USB Port
Audio Out –
Speaker / Headphone
Audio In - Mic

28. The Components of a Computer
• Storage
Storage mediaStorage media
Physical material on which data, instructions,
and information are stored
Eg: CD
Storage mediaStorage media
Physical material on which data, instructions,
and information are stored
Eg: CD
Storage deviceStorage device
Reads, Records and Retrieves items to and from
a storage medium
Eg: CD R/RW
Storage deviceStorage device
Reads, Records and Retrieves items to and from
a storage medium
Eg: CD R/RW
 Holds data, instructions, and information
for future use

29. Disk Capacity
It’s important to know how large your files are because
eventually you won’t have enough space on your disk to hold
more files.
Knowing the total capacity of your disk, how much space is left
on your disk, and how large the file is, you can make accurate
decisions as to whether to save the file to the current disk, or
save the file to a different diskette with more disk capacity.

30. • Floppy disk
 Thin, circular,
flexible disk
enclosed in rigid
plastic shell
 ~1.44 MB space
The CPU has places to insert disks.
A floppy disk drive reads information from floppy disk inside a
hard plastic case.

31. CD-ROM Disc Drive
CD-ROM stands for Compact Disk-Read Only
Memory. They are flat, shiny metal discs that
store information. CD-RW stands for Compact
Disk- ReWrite. This type of disk allows you to
write information to it, as well as read from it.
Most can hold up to ~700 megabytes of
information.
DVD Drive / Burner
The computers also come with the option of a
DVD drive. A DVD (Digital Video Disc) looks just
like a CD, but holds much more information!
They can store 4.7 gigabytes of data! DVD –
ROM & DVD - RW

32. Flash Drive / Pen Drive / USB Drive
A Flash Drive is a relatively
new storage device. It’s
like a mini, portable hard
drive! You plug it into the
USB (Universal Serial Bus)
port and you can save to it!

33. 33
•Memory Cards -
Miniature storage
media
Digital
cameras
Digital
cameras
Handheld
computers / Smartphones
Handheld
computers / Smartphones
Portable, thin
memory cards
used in:
Portable, thin
memory cards
used in:

34. • Portable Hard Disks

35. SYSTEM COMPONENTS
• Power Supply
• 250 – 500 Watts
• DO NOT OPEN
• (This is the power source that
makes everything go).
Power Supply
You can see the power supply from the
back of your computer because of the
power cord and the cooling fan.
Computers put out a LOT of heat and
need the fan to keep them from
overheating.

36. Power Supply
If there is any one component that is absolutely vital to the operation of a
computer, it is the power supply! Without it, a computer is just a box full of
plastic and metal.
The power supply converts the alternating current (AC) line from your home
or school to the direct current (DC) needed by the computer.

37. POWER PROTECTION
• Uninterruptible Power
Supply
• (UPS) 280 VA – 400 VA
• Essentially a battery
back-up in case of a
power failure

38. Thank You