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Classification of Computers
7/30/2019 4.Classification of Computers
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Anitha Padmanaban ACET
Introduction
Computers are broadly classified into
Based on Operating Principle
Based on applications
Based on size and capability
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Based on Operating Principle
Based on operating principles, computers are
divided into
Analog Computers
Digital Computers
Hybrid Computers
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Analog Computers
Represent data in the form of continuous
electrical signals having specific magnitude
Allows different operation to be performed atsame time
The electronic circuit used in analog computer is
Operational Amplifier (Op-Amp)
Op-Amp is made up of semiconductor
integrated circuits
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Characteristic Feature of Analog
Computer
Large voltage gain
Voltage gain is defined as the ratio of the output voltage
to the input voltage
Infinite input resistance
Input resistance is defined as the ratio of change in input
voltage to the change in input current
Zero output resistance The output resistance is the nominal resistance
measured with no load
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IC of an Op-Amp
Amplifier
Input Resistor Feedback
Resistor
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Analog Computers
Advantage
Very fast in their operation
Allows several operations to be carried out at the
same time
Powerful tool that solve differential equations
Disadvantage
Does not produce accurate results
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Analog Computer
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Digital Computer
Also known as digital information processing
Stores and processes data in digital form (0’s &
1’s)
Produce the output in digital form
Capable of processing analog data
Analog data is converted into digital data
Conversion of digital to analog data are done by
bulit-in function
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Hardware Components
1. Arithmetic Logic Unit (ALU)
Performs various arithmetic operations like
Addition
Multiplication
Subtraction
Division
Logic operations like AND, OR, NOT
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Hardware Components
2. Control Unit (CU)
Helps in directing the operations of ALU
3. Memory Unit (MU)
Stores data in temporary or permanent basis
4. Input Unit
Enter the data into the computer
5. Output Unit
Displays the information generated by the computer to
the user
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Digital Computer
Advantage
Faster and more reliable
Can be used in home, colleges, universities, etc
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Hybrid Computer
Combination of analog and digital computer
Data is measured and processed in the form of
electrical signals and stored with digitalcomponents
Can be used to perform various types of logical
operations
Accepts continuous input signals and convert
them into set of discrete values
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Hybrid Computer
Advantage
Very fast
Efficient
Reliable
Less expensive than digital computers
Disadvantage
Cost –effective to perform complex operation
Applications Hospitals: to measure the heart beat of patient
Scientific applications, Engineering fields, Controlling business
processes
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Based on Applications
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Based on Applications General Purpose Computers
Works in all environments
Versatile
Can store number of programs
Not efficient
Consume large amount of time in generating result
Special Purpose Computers
Performs only specific function
Not versatile
Speed and memory size depend on the task to beperformed
Less expensive
Do not contain any redundant information
Efficient and consume less amount of time in
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Based on Size and Capability
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Size and Capability
Computers differ from each other in terms of shape, size and
weights
Each type of computer perform some unique functions
On the basis of size and capability, computers can be classified
into
Micro computer
Mini computer
Mainframe computer
Super computer
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Micro Computer
Small and cheap digital computer
Hardware Components
Built around a microprocessor, a storage unit and an
I/O channel
Also contains power supply, connecting cables,
keyboard, mouse, printer and scanner
Software Components
Operating system, System software and Utility
software
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Block Diagram of Micro
Computer
Microprocessor
Peripheral devices
Interface Circuitry
Memory
System Bus
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Microprocessor
Heart of microcomputer
Incorporates all the functions of CPU on to a single IC
Basic units are
ALU
Perform various arithmetic operations
Register unit
Used to store the data and instructions temporarily needed by ALU
Includes Accumulator, Program Control, I/O, Instruction register,
Memory Address Register (MAR) and Memory Buffer Register
(MBR)
Control unit
Used to manage and direct operations performed by
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Microprocessor
Depending on the size the microprocessor are
further classified into
Desktop computers
Laptop computers
Hand-held computers
Etc……
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Memory Used to store the data and instructions
Two types of memory
Primary memory
Also called as main memory
Used to store data temporarily
Secondary memory
Also called as auxiliary memory
Used to store data permanently
Example
Magnetic disks, magnetic tapes, etc
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Peripheral device
They are generally the input and output devices
The various input devices are
Keyboard and mouse
The various output devices are
Monitor and printer
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System Bus
Also called as front side bus, memory bus, local
bus or host bus
Used to connect microprocessor, memory andperipheral device into a single unit
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Mini Computers
First introduced by Digital Equipment Corporation in
1960
Smaller in size
Can handle more data and more input and output
More powerful than micro computer
Can support 4 to 200 users at same time
All desktop computers can be connected to a single mini
computer
Handle 1000s of transactions in a day
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Main frame computers
Very large computer
Used for large scale business organizations
Capable of handling millions of records per day
Bigger and more expensive
Predecessor of servers
Occupies large space
Can maintain large databases
Also known as super servers or database servers
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Characteristics of main frame computers
Maximum of 16 microprocessors
RAM storage lies between 128 MB and 8 GB
Run multiple operating system
Different cabinets for primary storage, secondary
storage and I/O units
Can handle huge amount of operations at the
same time
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Super Computers
Fastest type of computer
Perform complex operations at a very high speed
Developed by Seymour Cray in 1960 at ControlData Corporation (CDC)
More expensive
Example: CRAY 3, Cyber 205, NEC SX-3 and
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