This document discusses different types of computer systems based on operational principle and size/speed. There are three types based on operational principle: analog computers that process continuous values, digital computers that process binary digits, and hybrid computers that can process both analog and digital data. Based on size and speed, there are supercomputers that are the most powerful, mainframes for intensive tasks, minicomputers for complex computations, and microcomputers which are the most common and include PCs.

1. Types of Computer System
Mr. Roshan Bhattarai
Kathmandu, Nepal

2. Types of Computer System
Classification on the basis of operational principle
– Analog
– Digital
– Hybrid
Classification on the basis of speed/size
– Super
– Mainframe
– Mini
– Micro

3. On the basis of operational principle
i) Analog Computers
• Analog computers process values that have continuous range
rather than digital values (0’s or 1’s)
• work with natural phenomena and physical values like frequency,
temperature, pressure, speed, earthquake, water flow, current
flow etc.
• generally used in scientific work, not for commercial or personal
purpose. Eg: speedometer, seismograph (ground motions) etc.
Some of its characteristics are listed below:
– Based on continuous varying data,
measures only physical values.
– Used for special purpose, low memory size
– Processing is faster but accuracy of
processing is relatively low

4. ii) Digital Computers
• Digital computers process digital values.
• Digital refers to the processes in computers
that manipulate binary numbers (0’s and 1’s)
• Meaning of 0 is off and 1 is on, the basic principle of these
computers is either presence or absence of electric current
• Examples: IBM PC, MacBook, Smartphones etc.
Some major characteristics of these computers are listed below:
– Based on discrete data (non- continuous)
– Based on the principle of logic 1 and 0 or on and off.
– Used for general purpose (multipurpose)
– Larger storage capacity because the calculations are to be stored
internally for future use.
– Processing is relatively slow but processing accuracy is higher

5. iii) Hybrid Computers
• Hybrid computers can perform the work done by analog
computers as well as by digital computers, can transfer data
from analog to digital and vice-versa
• Digital component- provides logical and numerical operations,
• Analog component- serves as a solver of differential equations
and mathematically complex calculations
• generally used in hospitals, airplanes, engineering, scientific
research etc. Eg: CT Scan Machine, Ultra Sound Machine
Some of the major characteristics are given below:
• Combination of analog as well as digital computer,
can process both continuous and digital data
• special purpose machines
• mostly used in hospitals and airplanes
• higher cost

6. On the basis of speed and size
i) Super Computer
• fastest, most expensive and powerful machines
• built by interconnecting large number of processors in parallel
• highest processing speeds and
• used for solving extremely complex problems
– biomedical research,
– whether forecasting,
– aircraft design,
– space technology
– nuclear fusion etc

7. ii) Mainframes
• These are high-level computers designed for the most
intensive computational tasks
• can process several millions program instructions per second
• often shared by multiple users connected via terminals
• Large organizations relay on these systems to handle large
programs with lots of data
• These are mainly used in centralized
databases, centralized server in WANs etc.

8. iii) Minicomputers
• These computers are mid range computers built to perform
complex computations
• They can handle multiple terminals and is widely used as
servers in networked environment
• used to control machines in a manufacturing unit and for
distributed data processing
• These computers are used in education, business and other
official sectors

9. iv) Microcomputers
• Most familiar kind of computer is the microcomputer
• use microprocessor as its central processing unit (CPU)
• Includes PC’s (desktops, laptops, and palmtops) and workstations
• PCs are commonly used in everyday life as they provide
computational abilities at low cost to people
• Workstations are like a PC, but has more powerful microprocessor
• generally used by engineers, scientists, other professionals that
require a moderate amount of computing power and relatively
high quality graphics capabilities