Holy Cross of Davao College
Sta. Ave., Davao City
BLIS In- House Review for Librarians’ Board Examination, August, 2005
Introduction of Information Technology
The qualities of information
How can we determine of the information received from an information system is
appropriate for decision making ?
GIGO- “garbage in garbage out”
Managers must ask if the information
a. timely
b. accurate
c. verifiable
d. relevant
e. complete
CLASSIFICATION OF THE DIGITAL COMPUTERS, AND SYSTEM
Introduction:
Computers system are classified as microcomputers, minicomputers, mainframes and
supercomponents.
MICROCOMPUTERS- THE MOST FAMILIAR KIND OF COMPUTERS IS
THE MICROCOMPUTERS. In the past microcomputers have been considered to be of
two types:
Example; Personal computers and workstations
 Personal computers (P Cs) were desktop or portable machines. These machines ran
comparatively easy to us applications software such as the word processors, spread
sheets, etc.
 Workstations- is again until recently expensive, powerful machines used engineers,
scientists, and others professionals who processed a lot of data.
 Portable computers- personal computing market is seeing the miniaturization
phenomenon. Now computers are becoming smaller yet more powerful.
 Laptops/Notebook- Laptops may be AC powered, battery powered or both. These
computers are ideal for users who have to work away form their office.
 Sub notebook- are for frequent flyers
 Personal digital Assistants (PDA) ARE MUCH MORE SMALLER THAN sub
notebooks. They combine pen input writing recognition.
MINICOMPUTERS- are also known as mid range computers are first develop as special
purpose mainframe computers. They were used for instance, to control
machines in a manufacturing unit.
DDP- Distributed Data Processing
Mainframe computers- can process several million-program instructions per second.
Mainly used
by insurance companies IBM is S/390.
SUPERCOMPUTERS- is the fastest calculating devices ever invented. A desktop
microcomputer processes data and instructions in billions of a second or
microseconds.
Used by government agencies.
NETWORK COMPUTERS- are computers with minimal memory, disk storage and processor
power designed to connect to a network, specially the Internet.
SYSTEMS:
A SYSTEM- is a group of related elements that work together toward common goal.
A system is made up of input, processes and output
A. Input – enters the system form the surrounding environment and is transformed by some
processes.
INPUT DEVICE – is any machine that feeds data into a computer.
Examples:
 KEYBOARD – consist of
- alphanumeric keys-letters and numbers;
- punctuation keys; comma, semicolon, and so on- special keys; function keys, control keys arrow keys, cap lock key and so on
 QWERTY – is the standard lay out of letters and punctuation.
There are three different PC keyboard.
1. original PC keyboards (84 keys)
2. AT keyboards
3. Enhanced keyboard (101 keys)
IBM keyboards contains (page up page down, home, end, insert, pause, num. Lock, scroll lock,
break caps lock, print screen)
 MOUSE – is a device that controls the movement of the cursor or pointer on a
display screen
3 TYPES of MOUSE
a) Mechanical – has a rubber or metal ball on its underside that can roll in all directions.
Mechanical sensors within the mouse detect the direction the ball is rolling,
b) Opto mechanical – same as mechanical mouse, but is opticcal sensors to detect
motion of the ball.
c) Optical – uses a laser to detect the mouse movement.
 MUSE PAD – is a pad over which you can mouse. It provides more traction than
smooth surface such as glass and wood.
 TRACKBALL – is another pointing device. Essentially a trackball is a mouse lying
on its back. It is stationary so it does not require much space to use it.
 JOYSTICK – a lever that moves in all directions and controls the movement of
pointer or some their display symbols.
 DIGITIZING TABLET – an input device that enables you to enter drawing and
sketches into a computer. It consist of electronic tablet and a cursor or a pen.
 SCANNERS – is an input device that can read text or illustrations, printed on paper
and translate the information into a form that the computer can use. It works by
digitizing an image.



 SCANNING TECHNOLOGY – most scanner use charge-coupled device
(CCD arrays)
 RESOLUTION – the denser the bit map, the higher the resolution. Typically
scanner support resolution 72 to 600 dots per inch. (dpi)
 BIT DEPTH – the number of bites used to represent each pixel.
 SIZE AND SHAPE – some scanners are small hand held devices that you
move across the paper.
DIGITAL CAMERA – image can be input into a computer using a digital camera.
This images can then be manipulated in many ways using the various imaging tools
available.
MAGNETIC INK CHARACTER RECOGNITION (MIRC) – allows the
computer to recognize characters printed using magnetic ink. MIRC is direct entry
method used in banks.
OPTICAL CGARACTER RECONGITION (ORC) – refers to the branch of
computer service that involves reading text from paper and translating images into a
form. It includes optical scanner for reading text and sophisticated software.

OPTICALMARK RECOGNITION (OMR) – also called mark sensing is a
technology where an OMR device senses the presence or absence of a mark, such as
pencil mark. OMR is used in test such as aptitude test.
 BARCODE READER – is a photoelectric scanner that read the barcode, or vertical
zebra striped marks printed on product containers. Supermarkets used barcode system
called Universal Product Code (UPC)
 SPEECH INPUT DEVICE – speech or voice input device converts a person’s
speech into digital form. This input device when combined with appropriate software
form voice recognition system.
 TOUCH SCREEN – touch screen is a type of display screen that has a touch
sensitive transparent panel covering the screen.
 TOUCH PAD – a small touch sensitive pad used as pointing device of some portable
computers
 LIGHT PEN – is an input device that butlizes a light sensitive detector to select
objects on display screen.
FOUR FUNCTIONS OF THE COMPUTER:
1. Receives input-accepts information from outside through various input devcies like the
keyboard, mouse and etc.
2. Process information – performs arithmetic or logical operations on the information.
3. Produce output – communicates information to the outside world through output device like
monitor printer, etc.
4. Store information – store information in storage devices like hard disk, floppy disk.
PROCESSES:
PROCESSES – performs arithmetic or logical operations on the information
- the brains of the computer are the processing and main memory devices house
in the computer system unit
CPU – the system unit or system cabinet, houses the electronic circuitry called CPU. It
does the actual processing and the main memory, which supports the processing.
It controls and manipulates data to produce information. In personal computer the
CPU is usually a single fingernail size “chip” called microcomputers with
electrical circuit printed on it, mounted on a system board or motherboard.
- The part of the computer that executes program instruction
- It has two parts
- Control unit
- Arithmetic logic unit (ALU)
Control Unit – tell the rest of the computer system how to carry out a program’s instruction. It
directs the movement of electronic signals between memory, which temporarily
holds data’s instruction and processed information and the ALU
Arithmetic Logic Unit (ALU) – usually called the ALU performs two types of operations,
arithmetic and logical.
Memory – also known as the primary storage or main memory is a part of the microcomputer
that holds data for processing, instruction for processing the data (the program) and
information (processed)
REGISTERS – additional storage location. It appears in the control unit and ALU and make
processing more efficient. Holds data and instructions temporarily during
processing. They are parts of control unit and ALU.
ADDRESSES – to locate characters of data or instructions in the main memory, the computer
stores the in location known as addresses. Addresses can be compared to post office
mailboxes.
Contents continuously change, and number stay the same.
OUTPUT DEVICES
Output – is anything that comes out of a computer. It is meaningful information or gibberish and
appear in a variety of forms as binary numbers, as characters, as pictures, and as
printed.
AN output device is any machine capable of representing information from a computer. It
includes display screens, loudspeakers, printersplotter, etc.
MONITOR – is another term for the display screen. It refers to the entire box, where as display
screen can mean just the screen.
CLASSIFICATION OF MONITORS BASED ON COLOURS:
1. Monochrome – monitors that display two colors. One for the background and one for the
foreground. It can be black and white and green and black, or amber and black.
2. Grayscale – a grayscale monitor is a special type of monochrome monitor capable of
displaying different shades of gray.
3. Colour – monitor can display anywhere from 16 to over 1 million different colours.
Sometimes called RGBN – red, blue and green.
CLASSIFICATION OF MONITORS BASED ON SIGNALS
Digital monitor – accepts digital signals rather analogy signals. Fast and produce clear images
but cannot display variable colors.
Analog monitor – traditional type of color display screen that has been used for years in
television
BANDWIDTH – the amount of data that can be transmitted in a fixed amount of time.It is
expressed in cycles per second on Herts, (Hz)
Refresh – display monitor must be refreshed many times per second.
Dot pitch – a measurement that indicates the vertical distance between each pixel on a display
screen
Convergence – refers to how sharply an individual colour pixel on a monitor appears. Each pixel
is composed of three dots.
VGA (Video Graphics Array) – a graphics display system for PC’s deevloped by IBM.
SVGA (Super Video Graphics Array) – a set of graphics standards designed to offer a greater
resolution than VGA.
Printer – a device that prints text or illustrations on paper and in many cases on transparencies
and other media.
Daisy-Wheel Printer – are type of printer that produces letter quality type. A daisy-wheel
printer works on the same principle as a ball heard type writer. It cannot print
graphics and in general, they are noisy and slow.
G. Dot – Matrix Printer – dot matrix printer – creates characters by striking points against ink
ribbon. Each pin make a dot. Are inexpensive and relatively fast, but they do
not produce high quality output.
Speed – given a characteristics per second (CPS)
Printer Quality – determined by the no. of points
Inkjet Printer – works by spraying ionized wink Magnetized plats in the inks path dried the ink
onto paper in delude shapes.
Laser Printer – utilizes a lacer bean to produce an image on a dim.
LCD & LED printers – similar to a laser printer but uses liquid crystals or light-emitting diodes
rather than cases.
Line Printer – are high speed printers capable of printing a entire line at one time
Thermal Printer – are printers that produce on paper based on commands from a computer
Sound cards & Speakers an expansion board that enables a computer to manipulate and output
sounds.