Hardware and software

1. set of programs between application software and computer hardware
2. functions
   1. resource management
      1. managing computer hardware
   2. provision of user interface

      Nota:

      • (e.g. Windows) to allow users to perform tasks, e.g. running application software, changing settings on the computer, downloading and installing new software

1. designed to optimise the performance of computer
   1. OR perform tasks
      1. backing up files
      2. encrypting data before transmission
      3. providing a firewall
2. disk defragmenter

   Nota:

   • a program that reorganises a hard disk Files split up into blocks and stored all over the disk get recombined in a single series of sequential blocks - Makes reading a file faster
3. virus checker

   Nota:

   • checks hard drive, and possibly incoming emails and internet downloads, for viruses and removes them

Nota:

• in windows, often have a .dll extension

1. ready-compiled programs
2. grouped together in software libraries
3. Many compiled languages have their own libraries which can be invoked in the user's programs

1. compilers
2. interpreters
3. assemblers
4. translate program code into machine code

Nota:

• e.g. word processor, spreadsheet, graphics package can be used for many different purposes

Nota:

• performs a single specific task or set of tasks
• e.g. payroll and accounts packages, hotel booking systems, fingerprint scanning systems, browser software
• Software may be bought "off-the-shelf", ready to use, or it may be specially written by a team of programmers for a particular organisation

Nota:

• more expensive than ready-made package