Hardware and Software

Hardware and Software

1. Hardware

   • The physical parts that make up a computer system
     • Internal
       • e.g. CPU, RAM, ROM, HDD, SSD
     • External
       • e.g. MICR, OMR, OCR, cloud
   • Storage Devices
     • Purpose
       • Store data and software for later use
     • e.g. magnetic tape drive, optical, HDD, SSD
   • Input and Output devices
     • Purpose
       • Input
         • Provide/enter data for further processing in a computer or processing device.
         • Automatic
           • e.g. OMR, MICR, OCR
         • Manual
           • e.g. Keyboard, Graphics tablet, Digital camera, Scanner
       • Output
         • A piece of hardware that obeys a computer command to do something in the real world

2. System, application and user interface software

   • Software
     • The applications and programming instructions that tell the comouter what to do
     • Applications
       • Programs that allow the users to carry out certain tasks
       • Purpose
         • Word processors
         • Databases
         • Spreadsheets
         • Web Authoring
     • Systems
       • Programs that allow the applications software to communicate with the hardware
       • Purpose
         • Compilers
         • Linkers
         • Device Drivers
         • Operating systems and utilities
         • Interpreters
     • Utility software
       • A program designed to do 1 or 2 tasks very well and nothing else e.g. file sorting/renaming
         • Anti-virus
         • Back-up
         • Data compression
         • Disk defragmentation
           • Rearranging the information on a disc so that files appear in a continuous sequence of clusters
         • Formatting
         • Copying
         • Deleting
     • Custom vs Off-the-shelf
       • Custom
         • Software that is designed and developed for specific needs
           • Advantages
             • Can get exactly what you want
             • Will work exactly how they want it to work
             • Only have features that are specifically needed
           • Disadvantages
             • Takes a long time to develop (few months to a year)
             • Expensive
             • May need to employ a team for the system
             • Unlikely to find internet forums, more money has to be spent on training
       • Off-the-shelf
         • Used in home and school, e.g. word processors, provides many features (large storage size)
         • Advantages
           • Relatively cheap compared to written software
           • Easily availible from computer shops
           • Has been thouroughy tested- less bugs/problems
           • Lots of user support on the internet
     • Compiler and Interpreter
       • Function of a compiler
         • Translate source code into machine code
         • Translates whole program as one complete unit
         • Creates an executable file
       • Function of a interpreter
         • 1. Translates each line of source code into machine code and then executes the machine code directly
         • 2. Compiles source code into an intermediate level set of instructions, which are then executed by the interpreter.
           • Intermediate codes = BYTECODES
       • Compiler vs Interpreter
         • Advantages
           • Fast, creates executable file that can run directly on CPU
           • Easier to protect Intellectual Property- the machine code is difficult to understand
           • Unauthorized modification is difficult- executable is in form of machine code
         • Disadvantages
           • Debugging is more difficult
           • More likely to crash computer
           • Uses more memory
         • Advantages
           • Debugging is easier- each line of code analysed before being excecuted
           • Uses less memory, only 1 line of code is present at a time
           • Easier to modify- instructions at high level, easy to understand
         • Disadvantages
           • Slower- interprets code one line at a time
           • Weaker intellectual property
   • User interface
     • Command Line interface (CLI)
       • Allows user to directly interact with the computer by typing in instructions
     • Graphical user interface (GUI)
       • A friendly way for users to interact with the computer using pictures, graphics and icons (WIMP)
     • Dialogue Interface
       • Interacting with your environment by means of spoken word
     • Gesture based Interface
       • User uses hardware as an input device , which recognizes a gesture and sends it to the device, finding a predefined command to generate feedback back to the user