Computer Systems Servicing: Maria Luisa N. Francisco

COMPUTER
SYSTEMS
SERVICING
Maria Luisa N. Francisco
Computers covers every part of our
lives: the way we work, the way we learn,
the way we live, even the way we play. It
is almost impossible to go through a
single day without encountering a
computer, a device dependent on a
computer, information produced by a
computer, or a word that was introduced
or whose meaning has changed with the
advent of computers. Indeed it is difficult
to think of a field in which computers
are not used.
A major concern related to the use of
a computer is the digital divide, which
is the idea that the people of the world
can be separated into two distinct
groups:
•those that have access to technology
with the ability to use it; and
•those that do not have access to
technology or are without the ability to
use it.
Digital divide exists in variety of levels; sector,
community, and individual level. There are at least
three major divides:
•A global divide between the developed and

undeveloped worlds
•A social divide between individuals in higher
income levels that have greater access to
computers than people in lower levels, and the gap
may be growing.
•A democratic divide between those who do and
those who do not use the new technologies to
further political participation.
In reality computers play a
significant part in today’s world,
it is important to be computer
literate. Being computer
literate means you have the
knowledge and understanding
of computers and their uses.
OMPUTER
•is an electronic device designed to send,
manipulate and receive data so that useful
information will be gathered and generated.
•is an electronic machine, operating under the

control of instructions stored in its own
memory, that can accept data, manipulate the
data according to specified rules, produce
results, and store the results for future use.
Principal Characteristics
Of A Computer
•it responds to a specific set
of instructions in a well-defined
manner
•it can execute a prerecorded list of
instructions (a program).
BASIC ELEMENTS OF A COMPUTER
1. Hardware- the computer and all the equipment
attached to it. The actual
machinery — wires, transistors, and circuits
2. Software -the instructions that tell the computer

what to do.
3. Peopleware-represents the personnel involved in

systems analysis, programming, computer
operations, system maintenance and the like.
Hardware Components Of A Computer
Input-Process-Output
A computer first takes input from the user then process it

into C.P.U after that its display the result on the monitor.
Input device is any hardware component
that allows a user to enter data and
instructions into a computer.
•Keyboard
•Mouse
•Microphone
•Scanner
•Digital camera
•PC camera. /
Computer
webcam
Computer Keyboard- is a typewriter-style
device which uses an arrangement of buttons or
keys to act as a mechanical lever or electronic
switch.
TOP ROW KEYS
BOTTOM ROW KEYS HOME ROW KEYS

Mouse- sometimes called
a pointer,
is a hand-operated input device
used to manipulate objects on
a computer screen.
Processing Device
•The CPU which is responsible for the
processing and control of all the data flowing
into, out of and around the system.
•The processing hardware in a computer is

accountable for storing and retrieving
information.
•This part of the computer takes information

that is inputted by the user and processes the
information by calculating, comparing and
copying it and is then saved to the computer's
memory (RAM) Random Access Memory.
•System unit is a box-like case made
from metal or plastic that protects the
internal electronic components of the
computer from damage.
•Central Processing Unit (CPU) - is the

electronic device that interprets and carries
out the basic instructions that operate the
computer.
Output device
-- is any hardware component that can convey
information to a user.
•Printer
•Monitor
•Speakers
•Projector
•Plotter
MONITOR
is often used synonymously
with "computer screen" or
"display." ...
•Monitors built using LCD technology

commonly referred to as flat screen displays..
•These thin monitors take up much less space

than the older CRT displays.
Automatic
Voltage Regulator,
AVR is a hardware
device used to
maintain a voltage
to electronic
devices
Uninterruptible Power Supply (UPS) is a
device that allows a computer to keep running
for at least a short time when the primary
power source is lost. It also provides
protection from power surges.
2. Software -the instructions that tell the computer
what to do.
Types Of Software
A. System software - consists of the programs
that control the operations of a computer and its
devices.
oOperating System (OS) - coordinates all
activities among hardware devices and contains
instructions that allow you to run application
software.
oUtility Program - performs specific tasks,
usually related to managing a computer, its
devices, or its programs.
B. Application software - consists of programs that
perform specific tasks for users.
oPackaged Software - copyrighted software that

meets the needs of a variety of users
oCustom Software - tailor-made software developed

at a user’s request
oFreeware - copyrighted software provided at no cost
oPublic-domain software - software donated for

public use with no copyright restrictions
oShareware (copyrighted software distributed free for

a trial period).
3. Peopleware
a. EDP Manager- The person responsible for

supervising the data processing staff.
6
b. System Analyst- responsible for designing
counting systems, developing data processing projects
and developing specifications for applications
programmers.
c. Applications Programmer- responsible for

developing and testing new applications programs and
changes existing programs that meet the
specifications established by the System Analyst.
d. Systems Programmer- responsible for maintaining and
adapting the operating system and other systems software.
e. Computer Operator- responsible for the human

intervention required to run application programs, such as
mounting tapes onto tape drives.
f. Data Entry Clerk- responsible for handling and control of

data within the EDP department, including comparing control
totals to manually establish or data prepared totals and
correction of errors.
g. Librarian- responsible for maintaining and releasing for

authorized use, files maintained off-line and written
documentation of production programs.
Different types of computers
Operational Principle
1.Analog
2.Digital
3.Hybrid
Analog Computers:
---- are almost extinct today.
---- can perform several mathematical operations
simultaneously.
---- It uses continuous variables for mathematical
operations and utilizes mechanical or electrical
energy.
Digital Computers:
•They use digital circuits and are designed to operate
on two states, namely bits 0 and 1.
•Suitable for complex computation and have higher
processing speeds.
•They are programmable.
•Can either be general purpose computers or special
purpose ones.
• Special purpose computers - are designed for
specific types of data processing
• General purpose computers -- are meant for
general use.
Hybrid Computers: These computers are
a combination of both digital and
analog computers. In this type of
computers, the digital segments
perform process control by conversion
of analog signals to digital ones.
Classification of computers based on their
sizes and processing powers
Processing Power
1.Mainframe
2.Microcomputers
Mainframe Computers: Large organizations use
mainframes for highly critical applications such
as bulk data processing and ERP. Most of the
mainframe computers have capacities to host
multiple operating systems and operate as a
number of virtual machines. They can
substitute for several small servers.
Microcomputers:
• A computer with a microprocessor and its
central processing unit.
•When supplemented with a keyboard and a
mouse, microcomputers can be called
personal computers.
•These computers can fit on desks or tables
and prove to be the best choice for single-
user tasks.
Personal Computers
1. Desktop
2. Laptop
3. Netbook
4. PDA
5. Minicomputer
6. Server
7. Supercomputer
8. Wearable Computer
9. Tablet
Desktops:
•is intended to be used on a single
location.
•the spare parts of a desktop computer are
readily available at relatively lower costs.
•Desktops are widely popular for daily use
in the workplace and households.
Laptops:
• are miniaturized and optimized for mobile use.
•runs on a single battery or an external adapter
that charges the computer batteries.
•they are enabled with an inbuilt keyboard, touch
pad acting as a mouse and a liquid crystal
display.
•their portability and capacity to operate on
battery power have proven to be of great help to
mobile users.
Netbooks
•fall in the category of laptops, but are inexpensive and

relatively smaller in size.
•they had a smaller feature set and lesser capacities in
comparison to regular laptops, at the time they came into
the market.
•But with passing time, netbooks too began featuring
almost everything that notebooks had.
•By the end of 2008, netbooks had begun to overtake
notebooks in terms of market share and sales.
Personal Digital Assistants (PDAs): It is a handheld
computer and popularly known as a palmtop. It has a
touch screen and a memory card for storage of data.
PDAs can also be used as portable audio players, web
browsers and smartphones. Most of them can access
the Internet by means of Bluetooth or Wi-Fi
communication.
Minicomputers:
•lie in between mainframes and microcomputers.
•are also called mid-range systems or workstations.
•began to be popularly used in the 1960s to refer to relatively
smaller third generation computers.
•took up the space that would be needed for a refrigerator or two
and used transistor and core memory technologies.
•The 12-bit PDP-8 minicomputer of the Digital Equipment
Corporation was the first successful minicomputer.
Servers:
• are computers designed to
provide services to client machines
in a computer network.
•They have larger storage
capacities and powerful
processors.
• Running on them are programs
that serve client requests and
allocate resources like memory
and time to client machines.
•Usually they are very large in size,
as they have large processors and
many hard drives.
•They are designed to be fail-safe
and resistant to crash.
Supercomputers
The highly calculation-
intensive tasks can be
effectively performed by means
of supercomputers. Quantum
physics, mechanics, weather
forecasting, molecular theory
are best studied by means of
supercomputers. Their ability of
parallel processing and their
well-designed memory
hierarchy give the
supercomputers, large
transaction processing powers.
Wearable Computers: A record-setting
step in the evolution of computers was
the creation of wearable computers.
These computers can be worn on the
body and are often used in the study of
behavior modeling and human health.
Military and health professionals have
incorporated wearable computers into
their daily routine, as a part of such
studies. When the users' hands and
sensory organs are engaged in other
activities, wearable computers are of
great help in tracking human actions.
Wearable computers do not have to be
turned on and off and remain in
operation without user intervention.
Tablet Computers: Tablets
are mobile computers
that are very handy to
use. They use the touch
screen technology.
Tablets come with an
onscreen keyboard or
use a stylus or a digital
pen. Apple's iPad
redefined the class of
tablet computers.

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COMPUTER

•A global divide between the developed and

•is an electronic machine, operating under the

2. Software -the instructions that tell the computer

3. Peopleware-represents the personnel involved in

A computer first takes input from the user then process it

BOTTOM ROW KEYS HOME ROW KEYS

•The processing hardware in a computer is

•This part of the computer takes information

•Central Processing Unit (CPU) - is the

•Monitors built using LCD technology

•These thin monitors take up much less space

oPackaged Software - copyrighted software that

oCustom Software - tailor-made software developed

oFreeware - copyrighted software provided at no cost

oPublic-domain software - software donated for

oShareware (copyrighted software distributed free for

a. EDP Manager- The person responsible for

c. Applications Programmer- responsible for

e. Computer Operator- responsible for the human

f. Data Entry Clerk- responsible for handling and control of

g. Librarian- responsible for maintaining and releasing for

•fall in the category of laptops, but are inexpensive and

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