Dilla University College of Medicine and Health

Sciences
Health Informatics

Delelegn Emwodew (BSc-HI, MPH-HI)

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Chapter 1
Introduction to Computer
3 Learning Objectives
At the end of this lesson the student will able to:
▹ Define computer
▹ Know the history of computer
▹ Understand basic characteristics of computer
▹ Identify different types of computer
▹ Know components of computer
4
Computer Definition
▹ A computer is an electronic device that receive input, stores
or process the inputs as per user instructions and provides
outputs in desired format.
▹ Computers can perform four general operations:
• Receive inputs from user
• Process the inputs as per user instructions
• Store the processed data in its memory
• Provide outputs to the user
5 Work Flow of Computer

Input Process Output

▹ Computer input is called Data.

▹ Output obtained after processing data based on users
instructions is called information.
6 History of Computer
▹ The computer has evolved from a large-sized simple
calculating machine to a smaller but much more powerful
machine.
▹ The evolution of computer to the current state is defined
in terms of the generations of computer.
▹ The development of computer through generation
evolved in the following areas: reducing cost, reducing
size, increase speed and improving reliability.
7 First Generation (1940 to 1956)
▹ Used vacuum tubes for processing and magnetic drums
for memory.
▹ The input - punched cards and paper tapes.
▹ The output was displayed as printouts.
▹ The instructions were written in machine language.
▹ Machine language uses 0s and 1s for coding of the
instructions.
8 Cont..
▹ Computers of this generation could only perform single task
at a time and they had no operating system.
▹ Carry out instructions in milliseconds.
▹ Enormous in size and required a large room for installation.
▹ Examples: Universal Automatic Computer (UNIVAC),
Electronic Numerical Integrator And Calculator (ENIAC), and
Electronic Discrete Variable Automatic Computer (EDVAC).
 Second Generation (1956 to
1963)
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▹ Used transistors instead of vacuum tubes
▹ Become smaller, faster, cheaper, energy efficient and
reliable.
▹ Used magnetic core technology for primary memory and
used magnetic tapes and magnetic disks for secondary
storage.
▹ The input - punched cards and the output using printouts.
▹ Instructions were written using the assembly language.
10 Cont..
▹ High-level programming languages, such as early versions
of COBOL and FORTRAN were also developed during this
period.
▹ Carry out instructions in microseconds.
▹ The cost of commercial production of these computers
was very high, though less than the first generation
computers.
▹ Examples PDP-8, IBM 1401 and CDC 1604.
11 Third Generation (1963-Present)
▹ The invention of integrated circuit (IC) brought us third
generation of computers.
▹ With this invention computers become smaller, more
powerful, more reliable and they are able to run many
different programs at a time.
▹ The use of IC chip increased the speed and the efficiency
of computer, manifold.
▹ The keyboard and monitor were used to interact with the
third generation computer, instead of the punched card
and printouts.
12 Cont..

▹ Operating system allowed different applications to run at

the same time.
▹ High-level languages were used extensively for
programming, instead of machine language and assembly
language.
▹ Carry out instructions in nanoseconds.
▹ Computers became accessible to mass audience.
▹ Examples - IBM 370, PDP 11.
 Fourth Generation (1971 to present)
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▹ The microprocessor brought the fourth generation of
computers, as thousands of integrated circuits were built
onto a single silicon chip.
▹ Semiconductor memory replaced by RAM
▹ Secondary storage became smaller in physical size and
larger in capacity.
▹ Development of pointing devices like mouse, and
handheld devices.
14 Cont..
▹ Operating systems (MS-DOS and MS-Windows) developed
▹ Graphical User Interface (GUI)
▹ High-level programming languages were used.
▹ Carry out instructions in picoseconds.
▹ Eg. The Intel 4004 chip was the first microprocessor.
▹ IBM introduced the first computer for home use.
▹ In 1984, Apple introduced the Macintosh.
15 Characteristics of Computer

▹ Speed: Computers can carry out millions of instructions

per second.
▹ Accuracy: Computers can process data in high degree of
accuracy.
• Error that may occur are due to human errors.
16 Cont..
▹ Storage Capacity: Computers can store a very large amount
of data.
▹ Versatility: Computers can carry out a wide range of work.
• People can use computers for different applications.
▹ Diligence: Computers can work for a longer period of time
without getting tired.
17 Types of Computer
▹ Micro Computer or Personal Computer
▹ Mini Computer or Mid-range Computer
▹ Mainframe Computer
▹ Super Computer
18 Micro Computer
▹ A small and single-user computer.
▹ Can be classified in to:
 Desktop PCs: Are PCs designed for use by an individual
at a fixed location.
 Portable PCs: Compact and portable PCs such as
laptop
19 Mini Computer
▹ A multi-user computer capable of supporting from 10 to
hundreds of users simultaneously.
▹ Medium sized computer.
▹ Computing power lies between microcomputer and
mainframe computer.
▹ More processing speed and storage capacity than micro
computers.
▹ Used as database server, web server etc.
20 Mainframe Computer
▹ A powerful multi-user computer capable of supporting
many hundreds or thousands of connected users
simultaneously.
▹ Faster processing and greater storage than minicomputers.
▹ Used in large institutions such as banks, airlines, and
insurance companies.
21 Super Computer
▹ An extremely fast computer that can perform hundreds of
millions of instructions per second.
▹ The most powerful of the four categories.
▹ Used for complex calculation such as weather forecasting,
nuclear science, rocket launching.
22 Components of Computer
▹ Computers are made up of:
• Hardware
• Software
23 Hardware
▹ A computer devices that we can see and touch.
▹ Hardware are involved in the data processing cycle as an
input, process and output.
▹ Hardware components:
• Input devices
• Memory
• Central processing unit (CPU)
• Output devices
24 Input Devices
▹ Devices used to input data & instructions into the computer
system.
▹ Translate data from that humans understand to a form the
computer understands.
▹ E.g. keyboard, mouse, scanner
25 Memory
▹ A devices used to store data or programs (sequence of
instructions) on temporary or permanent basis.
▹ Types of memory:
• Primary Memory
• Secondary Memory
 Primary Memory
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▹ Fast, expensive and short-term memory.
▹ The main working area of the computer.
▹ The CPU can utilize only those instructions and data that
are stored in primary memory.
▹ Two general parts:
1. RAM
2. ROM
27 Random Access Memory (RAM)
▹ A memory temporarily store data and programs for use
during processing.
▹ Processor access all memory address directly.
▹ It is volatile in nature, which means that data will be lost
when the computer is turned off.
▹ The more information being processed the more RAM the
computer needs.
 Read Only Memory
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▹ ROM is a permanent form of storage.
▹ It store data written during manufacturing phase.
▹ It can be only read by the processor.
▹ It contain data that can not be changed by users.
▹ Non volatile, stays active regardless of whether power
supply to it is turned on or off.
 Secondary Memory
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▹ A storage devices used to keep data and programs for later
use.
▹ Any storage device designed to retain data and instruction
in a permanent form.
▹ Non-volatile storage media.
▹ E.g. Hard disks, flash disk
 Central Processing Unit
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▹ CPU or microprocessor is the brain of a computer that
does all the work.
▹ It is the place where data processing takes place.
▹ It is an integrated circuit or chip which processes
instructions and data.
31 Main Parts of CPU
 The CPU consists of:
• Control Unit (CU)
• Arithmetic Logic Unit (ALU)
• Registers
32 Control Unit (CU)
▹ All parts of computer interact through control unit.
▹ Controls the entire operation of the computer.
▹ Determining which operations to perform and in what order
to carry out them.
▹ Instruct the hardware to perform the requested operation.
▹ Provide the necessary data to an ALU or register.
 Arithmetic Logic Unit
(ALU)
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 Consists of electronic circuits to perform:
▹ Arithmetic operations (addition, subtraction, multiplication
and division)
▹ Logical operations (and, or, not, …) and to make some
comparisons (less-than, equal, … etc.)
34 Registers
▹ A special storage location within CPU which temporarily
hold data and instructions while they are being processed.
▹ Stores the data that is to be executed next.
▹ It is connected to both the ALU and CU.
▹ To execute an instruction CU retrieves data from primary
memory and places it into a register and after processing the
results are stored in register.
▹ Holds intermediate results obtained during processing.
35 Output Devices
▹ Devices that translate the processed information from CPU
into a form that humans can understand.
▹ Use to display processed information to the user either in
softcopy or hardcopy.
▹ Soft copy: output displayed on a computer screen.
E.g. Monitor
▹ Hard copy: output produced on paper or micro film.
E.g. Printer
36 Software
▹ Software is a set of instructions or programs that direct
the computer hardware to perform a particular task.
▹ Categories of software:
1. System software
2. Application software
3.Utility software
37 System Software
▹ A software required to run the hardware components of the
computer and other application software.
▹ It converts all human instructions in to machine
understandable instructions.
▹ Types of system software:
• Operating system
• Language processor
• Device drivers
38 Operating System (OS)
▹ System software that manage the computer hardware to
perform their tasks successfully.
▹ It is an interface between hardware and user.
▹ Allow components to communicate with each other and
enables computer to run software applications.
39 Functions of Operating System
▹ Accepts inputs from a keyboard.
▹ Sends outputs to a display screen (monitor).
▹ Manages files and folders in the system (naming, creating,
moving, retrieving and deleting folders).
▹ Allows applications software to communicate with the
system's hardware.
▹ Manages system security (allows passwords to be added /
changed).
40 Operating System Interfaces
▹ The way in which users communicate with the computer is
called an interface.
▹ There are two types of OS interfaces:
• Command Line Interface (CLI)
• Graphical User Interface (GUI)
 Command Line Interface (CLI)
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▹ CLI is an older style of OS in which users interact with a
computer by typing commands.
▹ Accept input via keyboard only.
▹ All the user sees is a plain black screen.
▹ Because they use no graphics they require very little
computer power.
42 Cont..
▹ There are over 270 different commands that can be
entered at the command prompt. 
▹ Commands have to be entered precisely without
spelling mistakes or else the OS will return an error.
▹ Remembering commands and the exact way to enter
them can be difficult and so CLIs are difficult to use.
43 Examples: Unix, DOS
44 Examples of some commands

▹ copy: copies files from to another location

▹ del: deletes one or more files
▹ format: deletes all the data on a hard disk
▹ md: creates a new folder
▹ rename: renames a file or folder
45 Graphical User Interface (GUI)

▹ Is a type of user interface which allows user to interact

with computer with images (graphics) rather than text
commands.
▹ Accept inputs via keyboard and pointing devices.
▹ Instead of typing in commands, the user can use a mouse
to point and click objects on the screen.
▹ For example: a user can erase a file by right clicking and
then selecting delete.
46 Examples: Windows, Mac OS , Linux
47 Language Processor
▹ System software that converts all user instructions in to
machine understandable language.
▹ Programme written in high level programing languages like
java, C++, etc. is called source code.
▹ Language processor converts source code to object code to
be understandable by the computer.
48 Device Driver
▹ System software that controls and monitors functioning of
a specific devices on a computer.
▹ Each devices that need to be attached externally to the
system has specific driver associated with it.
▹ When you attach a new device, you need to install its driver
so that the OS knows how it needs to be managed.
49 Application Software
▹ A software that perform a single task.
▹ Here are some commonly used application software:
• Word processing
• Spread sheet
• Presentation
• Database program
• Multimedia tools
 Utility Software
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▹ A software that assist system software in doing their work is
called utility software.
▹ A cross between system software and application software.
▹ Examples of utility software include:
• Antivirus software
• Disk management tools
• File management tools
• Backup tools
THANKS!
Any questions?

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