Inside the system unit
The system unit is a magical box that you’ll
probably never need to open. But someday, you’ll get curious about what’s inside.
Inside a Computers Simplified
Inside a Computers Simplified
Inside a Computer -- Part of the
Computer Motherboard
Here’s
how to peek inside a desktop computer’s system unit.
· Make sure the computer’s turned off.
·
Remove the screws from the 4 corners of
the system unit’s back wall. Notice how big those screws are. Remove any other
screws of that size from the back wall’s edges.
·
Then remove the system unit’s cover:
·
If the unit’s a tower, pull the cover back
slightly, then lift it.
·
If the unit’s a desktop, slide the
cover forward — or if it refuses, try sliding the cover back — then lift it
slightly.
·
If
the cover doesn’t quite come off, jiggle it slightly,
and also double-check whether you’ve removed all the screws holding it in
place.
·
Finally, peek into the system unit and
admire the goodies within! To be safe, avoid touching them.
Inside
the system unit, you see several green plastic boards, called circuit boards
(because they have electric circuits on them). On each circuit board, you see
many black rectangular objects, called chips:
each chip contains a miniature electronic circuit inside!
The motherboard is a large
electronic board that is used to
connect the power
supply to various other electronic parts,
and to hold these parts in place on the computer.
The motherboard contains the
buses, or electrical pathways found in a computer. Buses allow data to travel
among the various components.
The motherboard accommodates CPU, RAM, expansion
slots, heat sink/fan assembly, BIOS chip, chip set, sockets, internal and
external connectors, various ports, and the embedded wires.
Also found on the motherboard is
the BIOS (Basic Input and Output System) chip that is
responsible for some fundamental operations of the computer, such as linking
hardware and software.
The motherboard also contains a small battery (that looks like a watch
battery) and the chips that work with it to store the system time and some
other computer settings.
The
layout or form factor determines what sort of casing the motherboard needs and
provides a maximum expansion slot limit. Making some parts removable enables
one to upgrade or expand system.
Upgrading means changing to newer, usually
more powerful or sophisticated versions such as more memory chips while
Expansion is a way of increasing a computer's capabilities by adding hardware
to perform tasks that are beyond the scope of the basic unit.
On the mobo, the biggest chip is the one that does
most of the thinking. It may be
likened to the Central Nervous System of an animal. That chip is called the central processing unit (CPU). It’s also called the microprocessor.
A standard computer uses a brand of
microprocessor called a Pentium, manufactured
by an intelligent California company called Intel.
Yes, in a microcomputer, most of the thinking is
done by a single chip, called the microprocessor.
In older,
bigger computers, the thinking is done by
a gigantic collection of chips working together, instead of a single
microprocessor chip. That collection is called the processor. The term
microprocessor was invented by folks amazed that a processor could be
made small
enough to fit on a single chip.
All other devices such as the
input, output and storage devices are connected to the CPU and are called
peripherals.
An instruction is made up of
operations that specify the function to be performed and operands that
represent the data to be manipulated.
For example if the instruction is to perform the operation of
multiplying two numbers, there are two things that need to be taken into
consideration that is:
What
the two numbers are, and
The job of the central processor
is to retrieve instructions and data from memory and to perform each operation.
Processor models were initially
named in numbers for example 80286 or simply 286. Some examples of the processors are 386dx,
386sx, 486DX2, 486DX4, 586 or Pentium 1, Pentium II, Pentium III, Pentium IV.
We now also have the AMD K-6
Processors. The type of processor
determines the speed and efficiency of the computer. Generally the higher the processor model
number, the faster the processor.
Processor Speed
The speed of the processor is measured in Megahertz (MHz)
which means million cycles or instructions every second. The speed of the computer is actually given
by the Clock of the computer which sends timed electrical signals
every second and provides the processor’s heartbeat.
A processor is made up of two functional units and a set of workspaces,
that is Control Unit, Arithmetic Logic Unit (ALU) and Registers respectively.
The Control Unit
The Control Unit is responsible for supervising the operation of the
processor. It does the fetch and execute
job, that is retrieving instructions from memory and executing them
accordingly.
The control unit is driven by a clock pulse. The rate of the clock directly affects the
processor speed and it is measured in Megahertz (MHz).
The Arithmetic Logic Unit (ALU)
As the name states this is responsible for all mathematical
operations.
It receives data from the Control Unit and performs either Arithmetic operations (add, subtract,
multiply and divide) or Logic
operations (making a comparison and take an action based on the result) for
example If A=2 End, Else Begin.
This example shows that if A is equal to 2 the program should end and if
not equal it should start the operation again.
What Are Registers?
Registers are storage locations inside the processor. Registers in the control unit are used to
keep track of the overall status of the running program.
Control unit registers keep
current instructions and the operands of the instruction. There are also ALU registers that store data
items that are to be added, subtracted, multiplied, divided or compared.
Besides the motherboard,
the system unit contains smaller circuit boards (called expansion cards) that snap into slots
in the motherboard.
The most important
expansion card is the video card. It manages the monitor. It includes the video
port, which attaches to the cable that comes from the monitor.
Another expansion card
is the sound
card.
It manages the stereo speakers and microphone and attaches to the cables that
comes from them.
Another expansion card
is the modem (pronounced “mode em”).
It manages phone signals and attaches to cables that come from the phone and
the phone jack.
If your computer is part
of a local-area network, your computer includes a network interface card (NIC), which attaches to the
network cable that comes from the network’s other computers.
The keyboard does not
have its own expansion card. Instead, the keyboard’s cable plugs directly into
the motherboard.
The three most popular
kinds of memory are ROM
chips, RAM chips, and disks.
ROM chips remember info permanently. Even if you turn
off the computer’s power, ROM chips continue to remember what they’ve been
told. The most important ROM chips are on the motherboard.
RAM chips remember info temporarily. They’re
electronic scratchpads that the CPU uses to store temporary reminders. For
example, they remember what problem the computer’s working on at the moment.
They get erased when you switch to a different computer problem or turn the
computer off.
In an old computer, most RAM chips are on the motherboard, where the RAM
chips are arranged in rows, 8 or 9 RAM chips per row. In a new computer, the
RAM chips are instead on tiny expansion cards, which snap into tiny slots on
the motherboard: each tiny RAM cards is called a single in-line
memory module (SIMM) and holds 3, 8, or 9 RAM chips.
Disks work slower than ROM chips and RAM chips but can hold more info. Like
ROM chips, disks can remember info permanently: unplugging the computer
does not erase the disks. To use a disk, you must put it into a disk drive, which reads what’s on the disk.
In a traditional computer, the system unit includes 3 disk drives, to
handle 3 kinds of disks:
A CD-ROM disk looks like a
Compact Disk (CD) that music comes on, but a CD-ROM disk contain computer data
instead of just music.
A floppy disk is made of flimsy material but comes encased is a
sturdy square jacket, which is typically 3½ inches on each side (though older
disks come in 5¼-inch jackets instead). You can insert the floppy disk
(including its jacket) into the floppy-disk drive. You can also remove
the floppy disk (including its jacket) from the drive.
The typical hard disk is made of hard material, hides in the hard-disk
drive permanently, and never comes out, so you never see it.
Each of those three
types has its own advantages:
CD-ROM and floppy
disks can be removed from their drives.
The typical hard disk
cannot.
You can edit info if
it’s on a hard disk or floppy disk,
but not if it’s on a
typical CD-ROM disk.
The typical hard disk
can hold lots of info.
The typical CD-ROM
disk holds less.
A floppy disk holds
even less.
The newest computers
can also handle DVD disks (which hold movies
and computer data) but don’t bother handling floppy disks.
The power cord
comes from
your office’s wall and goes into the back of the system unit. Look
inside the system unit, at the back wall, where the power cord goes in.
There you see,
inside the system unit, a big metal box, called the power supply.
Hands on Exercise for you. Kindly fit in all the inside parts of a desktop computer. Click on the image below:
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