Computer Science

Computer Science

1. Computer System

   • A system is a collection of parts that work together for a common purpose.
     • For a system to be useful, it must produce something – an output. It needs to receive and process inputs in order to produce outputs.
   • Computer systems are based on processing data and producing information.
     • They are fast, and the important thing about them is that they are programmable.
       • Computer systems are found in most electronic gadgets. For example, washing machines, cameras, burglar alarms and telephones
         • Computer systems used in electronic gadgets have all of the basic functionality that drives a desktop PC. There are input and output devices, storage, a processor and, most importantly, software.

2. Embedded systems

   • Software that is programmed to carry out a number of dedicated functions. For example, the software to run a washing machine is stored on a computer chip and embedded into the system.

3. Reliability

   • Aeroplane
     • On 7th October 2008 an airbus operated by Quantas started to pitch violently because of a fault in an inertial reference sensor, causing the auto-pilot to try to correct suddenly. Fortunately there were few major injuries on this occasion. The problem was caused by faulty data sensors providing incorrect information to an automatic control system.
   • IT industry
     • Badly designed IT systems failing to achieve the desired result can cost millions or even billions of pounds that cannot be recovered.

4. Standards

   • Standards agreed by the IT industry are an essential element of system design and development.
   • Open standards are agreed so that community developers can modify source code freely available in the public domain, and do so effectively.
     • Application independence: access to resources is not dependent upon a single application.
     • Platform independence: access is not restricted to a specific hardware platform.
     • Long-term access: resources are openly developed and updated.
   • Hardware standards go beyond simply connecting peripheral devices. Standards exist for all aspects of computer hardware, including: Visual displays and ports; Internal connections such as SATA or PCI; Hard drive characteristics; Motherboard architecture; Processor specification.
   • Software standards include agreement on various file types, enabling software to use data from other systems effectively: For example, a number of image file types exist including png, jpeg, GIF, TIFF and various others. Knowing what to expect in such a file makes it possible for software packages to deal with them.

5. Regulation

   • Data protection act
     • Data is valuable and must be protected, and the Data Protection Act attempts to regulate organisations that store data.
     • Data should:
       • be processed fairly and lawfully
       • be obtained for a specified and lawful purpose and used accordingly
       • be limited to the specified data, be accurate, and up to date
       • be kept only for as long as necessary for the specified purpose
       • be kept securely
       • not be transferred outside the EU
   • Computer misuse act 1990 and The Copyright, Designs and Patents Act
     • The Computer Misuse Act
       • Unauthorized access to computer material
       • Unauthorized access with intent to commit or facilitate a crime
       • Unauthorized modification of computer material
       • Making, supplying or obtaining anything which can be used in computer misuse offences
     • The Copyright, Designs and Patents Act
       • Protects intellectual property by making it illegal to copy software or music, images or photographs from the web, or to copy text from web pages to use as your own work. Protects intellectual property by making it illegal to copy software or music, images or photographs from the web, or to copy text from web pages to use as your own work.

6. Environment

   • Computer hardware disposal

7. Memory

   • The CPU in the computer fetches data and instructions from memory to process. This type of memory is called primary memory and it is the only memory the CPU can access directly.
   • RAM( Random Access Memory)
     • Computers need a lot of RAM to deal with the large amounts of data they need to make available at any one time for the CPU.
     • Adding more RAM to a computer will improve the performance of that computer by making more memory available for direct access from the CPU.
     • A typical laptop will have 6 GB of RAM or more available.
   • ROM (Read Only Memory)
     • The information on a ROM chip is often programmed at manufacture.
     • ROM is often used to store the boot program, a sequence of instructions to start the computer and load the operating system.
       • The boot program
         • Performs some basic checks
         • Finds the operating system
         • Hands over control to the operating system
     • ROM cannot be overwritten by the computer, hence Read Only Memory.
     • ROM does not need to contain very much data and is typically just 1 or 2MB in size
     • Many devices, including music players, mobile phones and cameras, need ROM to boot them up.
     • Since many of these devices have the operating system stored in ROM, the type of ROM used is changeable through a process called ‘flashing’, hence flash memory.

Images and files in the map