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Chapter Two

1. The difference between hardware and software

   • Hardware are components that you can physically touch e.g. the mouse and keyboard
   • Software is the programs used on the computer.

2. Standardisation and the impacts

   • Standardisation is a set of rules that manufacturers must follow
   • Impacts of standardisation range from:
     • There are many different standards and they are not always compatible. If you purchase a computer that is not part of the global standard, then all subsequent upgrades and parts may have to come from specific sources and are likely to be very expensive.

3. Input Devices

   • Keyboard – set of type-writer style keys that are used to input data and control commands to the computer. Three main layouts: QWERTY, Alphabetic and Dvorak. Concept keyboards are programmable where you can create your own keys.
   • Mouse – pointing device that can be used to select items on a screen.
   • Scanner – translates information into a form that a computer can use. For example: Bar-code – translates bars into numbers, Optical Mark Reader (OMR) – detects the presence or absence of a mark and translates it into values and a Magnetic card reader – takes information form a magnetic strip and converts it to usable data.

4. Output Devices

   • Monitor – takes signals from a computer and displays them on a screen.
   • Printers: Dot Matrix – impact printer. This means there is physical contact between print head and the paper through an inked ribbon. Colour and black & white, Inkjet – spray ink on paper and are relatively quiet. Colour and black & white. Cheap to run. Used in homes and offices and a Laser – high resolution non-impact. Quality in both colour and black & white. Running costs are high. Used mainly in businesses and often found in homes.
   • Plotters – mechanical device which produces printout using vector or coordinate graphics. E.g. maps and building plans.

5. Storage

   • Hard disks – main storage device for a computer. They hold the programs and the data.
   • Optical Disks
     • CD-ROM – storage of about 700MB
     • DVD – storage of about 4.7GB or more.
   • Tape drive – tape cassettes to store data and have very high storage capacity. Used for backing up.
   • Memory sticks – large storage capacity.

6. Specialist Items

   • Specialist Software
     • Text-to-speech system – takes the written texts and outputs it using a speech synthesiser. Useful for those who are visually impaired.
     • Magnifier – can zoom in on portions of the screen. Used for visually impaired.
     • Predictive texts – suggests the required word as the letters are typed so the user doesn’t have to type the whole word.
     • Sticky keys – allows keys to be pressed once and the system to act as if been held down.
   • Specialist Hardware
     • -Devices to help visually impaired: A braille keyboard – a keyboard with braille dots on the keys, A microphone – input device used with voice recognition software, A loudspeaker – an output device for texts or signals and a braille printer – an impact printer which can create braille on a page.
     • Devices to help physically disabled: A mouth-stick – a stick to control input with the mouth, A puff-suck switch (blow-suck tube) – a tube placed in the mouth and blown / sucked through, An eye-typer – when the eyes move a pointer on the screen is also moved and a foot mouse – a mouse that is controlled by the foot.

7. Different types of software

   • -Operating system – controls the allocation and use of hardware resources, such as, memory, CPU time hard disk space and peripheral devices. E.g. Microsoft Windows, Apple.
   • User interface – means which user can interact with an application or operating system. There are different types: Menu – on screen list of options, Form – an on-screen form in which to type data. • Command line – a space to type instructions and Natural language – a voice-based interface.
   • Utility software – small program that assists in the monitoring and the maintaining of the computer system. E.g. virus checks.
   • Application software – allow computer to be used to solve particular problems and perform particular tasks for the end user. E.g. spreadsheets and databases.

8. User Interfaces

   • Method by which the user communicates with the computer.
     • Command-based – the user types instructions at a command prompt to control what the computer does.
     • Forms – limited area on screen with boxes to fill in.
     • Menus – series of related items that can be selected. Either pop-up or pull-down. Usually categorised. Can be cascaded (one menu leads to another). Can be context sensitive. Can use GUI or text-based. Part of a WIMP.
     • Natural language – allows users to use their own language to communicate with the computer. Either spoken or written.