Classification or types of OPERATING SYSTEMS

8:40 PM

Type		Definition	Example of Use
Batch Processing System	Data or programs are collected grouped and Processed at a later date.		Payroll, stock control and Billing systems.

Real-time Systems	Inputs immediately affect The outputs. Timing is critical i.e. they are capable of influencing the source of the data e.g. control where data from sensors is Processed immediately and affect the outputs – Controlling some device. Timing is critical and the term real-time control System.		e.g. control of nuclear Power plants, oil refining, chemical processing and air traffic control systems.

Real-time transaction	Inputs immediately affect the outputs but timing is not critical. Each transaction is completed online as it arises e.g. booking systems – each booking is online and a database of bookings can be amended interactively and Very quickly whilst another user is locked out so cannot double book or alter that record at the same time.		Holiday and airline Booking system. Difference between real time and real-time Transactions. In real time, time is critical and delays can be catastrophic but in real-time transactions Systems there is no time criticality. E.g. poor speeds in airline control would be Dangerous but poor booking speeds would not be so crucial.

Online processing	Processing performed under the direct control of the CPU whilst the user remains in communication with the computer.

Offline processing	Processing which is done away from CPU.		E.g. batching together of clock cards, filling in OMR forms.
	Provides for interaction Between the job and the user, this may influence the course of processing. Such systems may be single-user (e.g. a personal Computer).		Word processing

Multi-access on-line	Any users linked by Workstations to a central computer such as in a network.		Holiday or airline booking System. One person must Be locked out when another is updating the file. This helps to prevent Double booking

Interactive processing	The user has to be present and program cannot proceed until there is some input from the user		Select from a menu at ATM.

Distributed system	Processing is carried out independently in more than one location, but with shared and controlled access to some common facilities.		Databases e.g. libraries.

Multi programming	Ability to run many Programs apparently at the same time.		Mainframe systems. Each job is allocated a small amount of processing time (Time slice) in turn.

Multi tasking	The ability to hold several programs in RAM at one time but the user switches Between them.		Usually uses GUI’s. Facilitates import and Export of data.