Examples include payroll and stock maintenance systems. Embedded software is used to control products and systems for consumer and industrial markets. For example key pad control on a micro wave oven, or fuel control in a sophisticated engine. They are designed to mimic the behaviour of an expert in some well defined field. As noted in Section 1 above, apart from a program that is being executed there is always one more program permanently stored in primary memory called the operating system .
Operating systems are advanced pieces of software provided by the manufacturers of computers.
Keeps track of all the files stored in secondary storage. Provides the means whereby a user can communicate with the computer, i.e. it provides a user interface . MAC-OS used by Macintosh computers. In the case of UNIX user commands are passed to the the computer using the keyboard. Creation, deletion and inspection of directories.