Learn about CPU, chip set, storage devices and mother board components used for
communication among devices
The CPU and Chip Set
The two major computer microprocessor manufacturers are Intel and AMD. Both of these
companies have a Power CPU and a Budget CPU. The Power CPU's are the Pentium series from
Intel and the Athlon XP from AMD. The budget CPU's are the Celeron from Intel and the Duron
from AMD. The CPU is about quarter of an inch in width with pins underneath it. It is usually
black or dark grey. The CPU will likely be the larger of the chips on the motherboard inside your
The CPU typically contains 2 components.
1. The Control Unit:
This unit coordinates the many operations of a computer system.
It receives messages from INPUT devices like Hard disk, Mouse and keyboard.
It then decodes the instruction from input devices and sends them to the ALU(Arithmetic
Logic Unit) to be acted upon.
Finally it sends the processed information into storage or to OUTPUT devices (like your
screen or printer).
2. The ALU (Arithmetic Logic Unit):
This is where the information is actually processed. The ALU can do:
calculations (adding, subtracting, multiplying and dividing).
logic functions (comparing numbers, letters or special characters and then making
decisions based on the results.)
Two kinds of storage: Temporary (primary) and permanent (seconday)
CPU uses temporary storage, called primary storage or memory, to temporarily hold data and
instructions while it is processing them. Primary storage is faster to access than permanent
storage. But when data and instructions are not used they are stored in permanent storage called
Secondary storage. Floppy disk, CD, Flash drive and hard drive are examples of secondary
Primary storage is provided by devices called memory or RAM (Random Access Memory).
RAM chips can be installed on the motherboard.
3 types of boards that hold memory chips are:
SIMM - Single Inline Memory Module
DIMM – Dual Inline Memory Module and
RIMM – Rambus Inline Memory Module
Most motherboards use DIMM. Any information stored in the RAM will be lost when the
computer is turned off.
Another kind of memory is ROM (Read Only Memory). BIOS and startup programs are stored in
Secondary storage is provided by floppy disks, Hard drives, CD ROM and Flash drives.
The Floppy disk stores very little data when compared to other devices like hard disk, CD-ROM
etc. The common floppy disk available in today's market stores 1.4 Megabytes of information.
The floppy is made of thin round film, which is coated with carbon and ferrous oxide.
Since the floppy is very delicate it is packed in jacket to protect it. It looks black in color.
The floppy drive allows you to access floppy diskettes. The Floppy drive is connected to the
Motherboard (computer) via a 34-pin ribbon cable, which in turn is connected to the floppy
controller. A PC can support up to two floppy drives. If it has two, they will be connected to the
same ribbon cable. Since floppy drives need power, one of the power connectors must be
attached to power supply. The Floppy disk comes in two sizes 5.25 and 3.5 inches in diameter.
The 5.25-inch drive is completely obsolete, but is still used on older computers.
A hard drive is a storage device located inside the computer. It is called hard drive because the
disks are located inside the box. The disks inside cannot be removed as in case of a floppy drive.
Like a floppy disk, hard drives also store programs and data. A hard disk stores more data than a
floppy disk and is more stable when compared to floppy drives.
Like RAM, hard-drive capacity is also measured in megabytes. Since most new hard drives have
capacities of over 1000 megabytes, the capacities are measured in gigabytes, equaling roughly
Many computers might have an IDE, SCSI or both installed. SCSI and IDE drives look quite
similar. They are both about the same size as a floppy drive. The IDE cable has a 40-pin
connector and is about 1.5 inches wide. The SCSI drives use a 2-inch-wide cable and 50-pin
connector. New computers have SATA or Serial ATA hard drives.