Chapter one
• Information technology (IT)
– the study, design, development, implementation,
support or management of computer-based
information systems
– deals with the use of electronic computers and
computer software to convert, store, protect, process,
transmit, and retrieve information
• Information System (IS)
– collects, processes, stores, analyzes, and
disseminates information for a specific purpose
• A Computer-based Information System (CBIS)
– an information system that uses computer and often
telecommunications technology to perform some or
all of its intended tasks
• E.g. Ethiopian Airlines reservation system
• Dashen Bank’s banking system
• Commercial bank ATM system etc
What is Computer Science
• a science concerned with information i.e.
representation, storage, manipulation or
processing and presentation
• computer Science uses a special device called
COMPUTER
• has different fields of specialization or subdisciplines
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Software engineering
Computer engineering (Architecture)
Automata theory
Database Architecture
Artificial intelligence
Communications
Human-Computer Interaction
Concurrent, parallel, and distributed systems
What is a Computer
• is an electronic device that accepts data,
performs computations, and makes logical
decisions according to instructions that
have been given to it; then produces
meaningful information in a form that is
useful to the user
• It saves time, space, money, labors
Characteristics of computers
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Speed
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Accuracy
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computer is accurate and consistent provided that the data and
the instructions are correct
Storage Capacity
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The ability of computers to store and process vast amounts
Durability and reliability
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They can operate error-free over long periods of time
Versatility
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The ability of the computers to carry out their instructions in a
very short period of time
a wide array of application
Even if the above main characteristics of computers
are increasing with time, the cost and size of
computers are decreasing.
Types of Computers
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Based on the operational principle
– Analog
– Digital
– Hybrid
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Analog
– operate by measuring
– deal with continues variables
– E.g
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Thermometer
Voltmeter
– Almost an extinct type of computer these
days
• Digital computers
– deal with discrete variables
– operate by counting rather than measuring
– operate directly up on numbers (or digits) that
represent numbers, letters, or other special
symbols.
– E.g. .
• Desk & pocket computers
• The general purpose computers
– have higher accuracy and speed
– on the principle of binary mathematics
• Hybrid computers
• combination of both Analog and Digital
computers
• Based on functionally
– Special purpose
– General purpose
• Special purpose computers
– computers that are designed for a specific task
– E.g. ATM,
• General purpose computers
– computers that perform many tasks without
specialization.
– E.g. Desktop Computers, Laptops, etc
• Based on size, capacity, speed and reliability
– Micro computer
– Minicomputer
– Mainframe computer
– Supercomputer
• Microcomputer
– A personal computer; designed to meet the computer needs of
an individual.
– Provides access to a wide variety of computing applications,
such as word processing, photo editing, e-mail, and internet.
• Desktop –
– A microcomputer that fits on a desk and runs on power from an
electrical wall outlet.
– The CPU can be housed in either a vertical or a horizontal case.
– Has separate components (keyboard, mouse, etc.) that are each
plugged into the computer
• Laptop
– A portable, compact computer that can run on an electrical wall
outlet or a battery unit.
– All components (keyboard, mouse, etc.) are in one compact unit.
– Usually more expensive than a comparable desktop.
– Sometimes called a Notebook
Minicomputers
• are bigger in size than the Microcomputer
systems
• can give parallel access to up to 100 users
Mainframe
• Large expensive computer capable of
simultaneously processing data for hundreds or
thousands of users.
• Used to store, manage, and process large
amounts of data that need to be reliable, secure,
and centralized.
• maximum I/O connectivity as they accommodate
huge disc farms.
• occupy an entire room and could cost over
million dollars they have almost become extinct
Supercomputer
• A computer that was the fastest in the
world at the time it was constructed.
• Can tackle tasks that would not be
practical for other computers.
– Typical uses
• Breaking codes
• Modeling weather systems
Handheld
• Also called a PDA (Personal Digital
Assistant).
• A computer that fits into a pocket, runs on
batteries, and is used while holding the
unit in your hand.
• Typically used as an appointment book,
address book, calculator, and notepad.
• Can be synchronized with a personal
microcomputer as a backup.
Application of Computers
• Learning Aids
• Entertainment
• Commercial or business applications
• Scientific – engineering and research applications
• Information Utilities
• Electronic Banking and Service
• Shopping from Home
• Weather and Environment
• Transportation
• Medical and Health Care
• Routine and dangerous Tasks
• Consultant (Expert system)