6.1 - Hardware and Software

• hardware
  • physical components
  • electronic/electrical
  • platform on which software executes
• software
  • sequences of instructions (programs)
  • understood and executed by hardware (in its circuits or in VM equivalent)
• Classification of software
  • system programs = control the operation of the computer itself (OS)
  • application programs = solve problems for users
• System software
  • layer/layers of software to enable users to operate comp without having to be familiar with internal working. Layers = system software
    • includes operating system etc
• Application software
  • program/programs designed to support user-oriented tasks not specific to computers (e.g communicating, looking up info, etc)
  • cannot execute unless first translated into lang of computer = machine code or a form executable by a computer
  • needs to be loaded to main memory and must be able to communicate with IO devices or other computers
  • may need to access or store information
  • Types
    • General purpose application software
      • appropriate for many application areas
      • cheap = price spread over large customer base
      • reliable = test on large customer base + experienced team
    • Special purpose application software
      • software for a particular application
      • reliable = test on large but specialised customer base + experienced team
    • Bespoke software
      • software written from scratch for a certain task
      • made when no general purpose or special purpose software exists that could do the job
• System software
  • operating system sftware
    • controls the operation of a computer
  • utility programs
    • designed to perform a commonplace task
    • formatting, partitioning, defragmentation, etc
  • library programs
    • collection of compiled routines that other programs can link to and use
    • linking may be done at compile-time or run-time
    • loaded run-time libraries remain resident in memory until the last executing application is closed
    • Windows: dlls
  • Translators
    • Compiler
      • high-level lang to machine code or other lower-level lang
    • Assembler
      • symbolic form of machine code (assembly language) to machine code
    • Interpreter
      • translates and executes a high-level language or intermediate language one satement at a time
• Role of operating system
  • Hide complexities of hardware
    • machine easier to use
  • Manage hardware resources
    • controlled allcation of processors, memories, IO devices among the various programs competing for them
    • manage data storage