Machines and Computational Models

  • Created by: lhf2
  • Created on: 29-07-15 15:17

The Input-Process-Output Model


input- flow of data into the process from outside the system

process- includes all tasks required to effect a transformation of the inputs

output- data and information flow out of the process

storage- holds the data when turned off

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Computational Models

Sequential Algorithms:

  • an algorithm that is executed in a sequence (one step at a time)
  • most computer algorithms are sequential. 

Parallel Algorithms:

  • can be done a step at a time on different proccessing devices and then combined to get result
  • many parallel algorithms are executed concurrently
  • non-parallel algorithsm are called sequential algorithms


  • don't have to be on different machines (could be in same chip)
  • act without centraliused control 
  • do seperate jobs and then come together to compare results 
  • often used in artificial intelligence
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Whole System Virtual Machines

A whole system virtual machines provides a complete system platform that supports running and execution of a complete operating system. 

The VM software must emulate the entire hardware environment and convert guest system operations to the equivalent OS calls

Advantage- user can have multiple virtual machines operating on the same computer (run independently)

Disadvantage- less efficient than a real machine as it access the hardware indirectly

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Virtual Machines

A Virtual Machine

  • any virtual machine is a combination of real machine and virtualising software 
  • called a guest
  •  further abstraction from the hardware (less performance that real machine because of the abstraction.)

A Process Virtual Machine is...

  • designed to support a single process and 1 program 
  • also known as an application virtual machines 
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