1. technology and computing
2. hardware
3. computer

Introduction to Computer Systems
CS-101
Lecture 2
By :
Lecturer : Asad Abd Elrashid
Department of Computer Science
College of Arts and Science
1
Content
Classification of Computers.
Computers based on Technology.
Computers for Organization.
Classification of Memory.
Computer Applications.
Advantages and disadvantages.
2
Classification of computers
Computers based on Technology
1. Digital Computer :
Using only 0’s and 1’s. Both can store in small size of
memory called bit. 8 bits equal to 1 byte.
2. Analog computer :
Process values which keep changing with time.
Data may be in voltages, frequencies, temperature, …etc.
E.g. Speedometer
3. Hybrid Computer :
It works as digital and analog computers so, it is called
analog-digital computer.
Accepts analog signals and converts into digital
Computers for Organization
1. Micro Computer :
It is powerful, easy maintenance and low cost. It is the
most common type of PC and commonly called as
desktop.
 Size is small
 Less storage
 The length of lines in the range 8-32 bits
 E.g.: IBM PC, PS/2
2. Mini Computer :
 Capabilities between main frame and micro computers.
 Called mid-range computers. Word length is 32 bits.
 It is used by small and mid-size business organizations.
Cont..
3. Main frame Computer :
 More powerful than micro computers
 Word length size is 48,60 or 64 bits
 High processing speeds
 Can store large amounts of data
 Used in research organizations, large industries, large
business and government organizations
 They need more electricity
 E.g.: IBM 3000 series, UNIVAC 1180
Cont..
4. Super Computers :
 Used for scientific and engineering applications.
 Word length is 64-96 bit.
 They can have very large data bases(uses more data).
 They can do one trillion operations per second.
 Used in the field of science, defense, designing and
launching missiles, weather forecasting and biomedical
research.
 Highest speed
 E.g: CRAY-3, HITAC S-300
Classification of Memory
1. Primary memory
 Directly used by the CPU .
 Very fast.
 Volatile memory: The memory that loses its contents
when the computer is turned off.(RAM)
 Since the CPU can read or write the data to the memory
they called as read-write memories.
 Eg. RAM (Random Access Memory): It is temporary
memory.
 Non volatile memory: store data permanently.
 E.g. ROM (Read Only Memory): The information
stored in it can be only read.
2. Secondary Memory
 It is the permanent memory which stores large amount
of information for a long time
 It’s also called back up memory or auxiliary memory.
 E.g. Floppy disc, hard disc, CD drive, DVD drive,
DivX drive
 Uses Magnetic property, magneto –optical property,
optical property, solid state memory
3. Cache memory
 It’s a high speed memory between CPU and main
memory.
 Higher speed
 It stores data and instructions that are currently to be
executed
Computer Applications
1. Science:Computer is used by scientists to analyze large quantity of
data in some area like(monitoring the earthquake,
Nuclear research, ..etc)
Used satellite launching and remote controlling.
2. Education:Computers are used for teaching(E-Learning).
Computer Applications
3. Medicine and Health:Diagnosing the illness using the computer images and
results; they know cause of the disease (scan, x-ray)
4. Engineering/Architecture/Manufacturing:Computer used for planning, designing and drawing the
layouts for house, roads, dams etc.
5. Communication:Send and receive e-mails, e-shopping, e-banking, ecommerce and e-learning etc.
Computer Applications
6. Business and banking :
 For administrative purposes, preparing salary bills.
 Used in banking, insurance sectors and marketing.
 Used in online payments, transactions, publishing and
online business.
Computer Applications
7. Governments:
 Used for weather forecasting, in military, satellite
launching and controlling, communication, egovernment …etc.
 For police force to search all information on criminals,
crime scenes, driving licenses etc.
8. Entertainment :
 Used in music industry, games, …etc.
 Computer animation and colorful graphics with
multimedia effect.
Advantages/Merits of computers
1. Speed:- very high speed and Speed is measured in
MIPS and BIPS.
2. Accuracy:-The results are very correct.
3. Reliability:-It gives correct and consistent result
always
4. Storage capability:- store large amounts of data
5. Versatility:- can do different types of jobs
6. Diligence:- it won’t get tired
Disadvantages/De-Merits of
computers
1. Non-Intelligent: It just do the given operations.
 It does not think.
 It does not possess any intelligent for analyzing the
problem.
2. Inactive:• If No power supply, it won’t work.
Editors
To enter
program and
edit it
Assembler
Converting
assembly
language
instructions to
machine
instruction by
a assembler
Debugging is Debugging is
easy
easy
E.g.: Turbo C E.g,: TASM
Compiler
Interpreter
High level
Line by line
language
compilation
translates into
machine
language
Debugging is Debugging is
faster
slow
E.g. TC
Eg: BASIC
computer
Thank you for your attention
19
Lecturer : Aasd Abd Elrashid