Chapter 2 Types of Computer

On the basis of Work

Digital

Micro

1. 
   Classification based on Work (or function or application)
   

1. 
   Analog Computer
   

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  Analog computers work upon continuous data.
  
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  Analog computers measure physical magnitudes such as voltage, temperature, current and pressure.
  
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  E.g. Thermometer, Speedometer etc.
  

2. 
   Digital Computer
   

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  Digital computers work upon discontinuous data.
  
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  These computers work on binary digits 0 and 1.
  
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  Two types of digital computers:
  

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  Special Purpose Computer – Digital Clock, Calculator
  
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  General Purpose Computer – PC in computer lab
  

3. 
   Hybrid Computer
   

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  Hybrid computers are computers that comprise features of analog computers and digital computers.
  
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  The digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations.
  
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  E.g. Computers used in ICU of hospital, jet planes etc.
  

2. 
   Classification based on Size
   

1. 
   Super Computer
   

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  Super Computers contain several processors which work together to make it immensely powerful and fast.
  
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  Used to forecast the weather and global climates, in military research and defense system.
  
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  Used in seismography, plasma and nuclear research, in encrypting and decoding sensitive intelligence information.
  
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  E.g. CRAY, NEC Super SXII, CYBER 205 etc.
  

2. 
   Mainframe Computer
   

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  Powerful multi-user computer used in large business organizations, examination, industries and defense to process complex data.
  
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  It uses several CPU for data processing.
  
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  More than 100 users can use at a time.
  
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  Used in Credit card processing, Air traffic control system etc.
  
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  E.g. IBM S/390, ICL 39 etc.
  

3. 
   Minicomputer
   

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  Larger and more powerful than most microcomputers but are smaller and less powerful than mainframe computer systems.
  
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  A multi-user computers and supports more than dozens of people at a time.
  
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  Used in university, large business organizations to process complex data.
  
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  E.g. PDP-11, VAX etc.
  

4. 
   Microcomputer
   

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  Microcomputer has its CPU on one microprocessor.
  
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  It is a single-user machine i.e. only one user can work at a time.
  
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  Commonly used in offices, homes, schools, shops to perform different data processing jobs.
  
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  E.g. IBM PCs, Apple Mac. etc.
  

3. 
   Classification based on Model
   

1. 
   XT (Extended Technology) Computer
   

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  It has 8086 or 8088 microprocessor.
  
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  Its processing speed is 4.7 MHz and cannot support GUI (Graphics User Interface) based OS.
  

2. 
   AT (Advanced Technology) Computer
   

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  It has 80286 or more advanced microprocessor and faster than XT Computers.
  
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  It supports GUI based OS (Operating System) and applications.
  

3. 
   PS/2 (Personal System -2 ) Computer
   

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  It uses refined architecture and faster than AT computers.
  
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  It is a laptop computer with rechargeable and battery based system.
  
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  It is operated with OS/2 operating system.
  

4. 
   Classification based on Brand
   

1. 
   IBM PC (International Business Machine Personal Computer)
   

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  These computers are manufactured by IBM Company.
  
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  IBM manufactured mainframe computers followed by mini and microcomputers.
  
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  The microcomputer manufactured by IBM Company is called as IBM PC.
  
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  These computers are more reliable, durable and have better quality.
  

2. 
   IBM Compatible
   

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  It has the same functional characteristics and the principles of IBM PC.
  
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  They are cheaper and their parts are easily available in the market.
  
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  Most of the microcomputers used in Nepal are IBM Compatibles.
  

3. 
   Apple/Macintosh Computer
   

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  Macintosh Computers are manufactures by Apple Company.
  
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  The Apple Computers have their own software and hardware and are different from IBM computers.
  
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  Most of the Desktop Publishing houses use Apple/Macintosh because they have high quality graphics.