Computing - Fundamentals of Computer Systems

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  • Created by: txrinrf
  • Created on: 27-03-16 16:12

Computer Systems

  • Computer - Electronic, programmable data processing machine
  • System - Collection of parts that wrok together for some defined purpose
  • Computer System - A collection of hardware and software that works together to achieve some data processing task
  • Systems recieve inputs from the outside. They process these inputs. They output the results of the processing
  • A system is seperated from the outside world by a system boundary (Interfaces)
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Importance of Computer System

Most aspects of our lives are affected by computer systems:

  • Improved quality in manufacturing 
  • Cheaper manufacturing
  • Faster access to information
  • Better decision making 
  • New ways of doing business e.g. Online shopping 
  • New ways of communicating e.g. SMS 
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Examples of computer systems

Holiday Booking

  • Input: Dates, destinations, credit card details
  • Outputs: itineraries, air tickets, hotel reservations
  • Processing: Check availability, produce documents

Satnav

  • Input: Signals from satellites, Input from user
  • Output: Route, places of interest, warnings
  • Processing: check position, locate on map, output map
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Types of Computer Systems

  • General Purpose - Designed to person multiple and can contain various applications e.g. smart phones and laptops
  • Dedicated systems - Specially produced to perform a single function or set of functions e.g. a ticket vending machine 
  • Control systems - Computer systems that control machinery, rather than produce output for humans to reat or respond to
  • Embedded Systems  - Computer systems that are part of a large systems and they are usually also control systems e.g. Car systems
  • Expert Systems - Computer systems designed to behave like human experts (Contain knowledge base, inference engine, an interface) e.g. used for making credit checks and diagnosing diseases 
  • Management information systems - Bring together the information from all parts of an organisation so that mangers can make sensible decisions e.g. Office automation systems automate workflow 
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Reliability

  • Computers can play a central part in many life or death situations e.g. aircraft navigation and control 
  • Medical computer systems innclude activities such as record keeping, diagnosing diseases and DNA sequencing 
  • Reliability is expected when new computer systems are made - Mistakes can lead to: down time, expensive errors, data loss and compromosed privacy
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Data Integrity

  • Integrity - Relates to data being accurate and consistent and makes sure that stored data reflects real world reality
  • Database systems have rules that prevent inconsistent changes being made to data
  • Data integrity can be compromised by: human errors, software bugs, hardware malfunctions and natural disasters
  • Risks to data can be reduced by: Backing up data regularly, controlling access to data via security and using error detection and correction software 
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Reliability and testing

  • Reliability is improved through testing
  • Testing is designed to uncover errors 
  • Testing can never be complete because: software is complex, testing is expensive and time consuming 
  • There are a large number of pathways in modern systems - there will always be errors 
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Standards

  • Standards - Conventions and rules for programming languages, operating systems, data formats, communications protocol etc.
  • Originally there were no standards and each computer manufacturer made up its own rules
  • Standards are important because they: enable equipment from different manufacturers to work together, make learning new systems easier, minimise waste, ensure fair play access to markets 
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De Facto Standards

  • De facto standards - Develop over time because of common usage - ensure that files and systems can be used by anyone
  • E.g QWERTY keyboard layout, Microsoft word
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De Jure Standards

  • De Jure Standards - De facto standards that have become so universally accepted that they have to be adhered to by law
  • Examples: ASCII, Unicode
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Proprietary Standards

  • Owned by an organsation and ensure compatibility between the company's products 
  • Often wifely used but are not approved by an independant standards body e.g. Windows 
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Industry Standards

  • Industry Standards - Set by recognised non-commercial organisations e.g. Americal National Standards Institute 
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Open Standards

  • Publicly available
  • Produced collaboratively
  • Not dominated by any one interest group
  • Not for profit and available for free
  • Sufficiently detailed 
  • Examples: HTTP, HTML, XML
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Ethical and Legal Issues

  • Ethical act - One that is morally right
  • Legal act - one that does not break any laws 
  • Widespread computer use has produced new legal and ethical challenges regarding: privacy, data security, access to sensitive data and copyright
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Data Protection

  • Most governments have enacted laws that are intended to protect the privacy of individuals e.g. UK Data Protection Act
  • Legislation is needed because it is easy to copy data, transmit data and match data and make judgements about people
  • Other Laws such as copyright designs and patents act & computer misuse act

Principles of Data Protection Laws, Organisations must:

  • Allow people to view data about them
  • Correct information is requested
  • Not use data in any way that may cause damage or distress
  • Allow people to state that their data is not to be sold
  • Protect data from unauthorised access
  • Only collect data for specified purpose
  • Not transmit personal data outside the European Economic area

Nowadays, a lot of cyber crime (crimes comitted with the aid of computers) are comitted & these criminals are difficult to find

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Environmental Issues

  • Computers can benefit and damage environment e.g. Reduces need for travel and transport of goods, can lead to more efficient products that last longer and use energy more efficient
  • Unused computer have to be disposed of - Contain toxic materials e.g. lead and cadmium
  • E-waste is often shipped to LEDCs and put in landfills (where toxic chemicals can leak into soil & release dangerous toxins when burned)

Computer use a lot of energy and so do data centres. Methods to reduce energy used by computers include:

  • Virtual servers rather than physical ones
  • Solid state storage uses less energy
  • Automatic standby switching 
  • Laying out equipment so that it can be cooled efficiently
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Comments

ShayCoalbran

good revison source really helped thanks :)

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