1. Types of Operating System
Type Definition Example of Use
Batch Processing System Data or programs are Payroll, stock control and
collected grouped and billing systems.
processed at a later date.
Real-time Systems Inputs immediately affect e.g. control of nuclear
the outputs. Timing is power plants, oil refining,
critical chemical processing and air
i.e. they are capable of traffic control systems.
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.
Real-time transaction Inputs immediately affect Holiday and airline
the outputs but timing is booking system.
not critical.
Each transaction is Difference between real-
completed online as it arises time and real-time
e.g. booking systems – each transactions. In real time,
booking is online and a time is critical and delays
database of bookings can be can be catastrophic but in
amended interactively and real-time transactions
very quickly whilst another systems there is no time
user is locked out so criticality. E.g. poor speeds
cannot double book or in airline control would be
alter that record at the same dangerous but poor booking
time. 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 e.g. batching together of
away from CPU. clock cards, filling in OMR
forms.
Provides for interaction Word processing
between the job and the
user, which may influence
the course of processing.

2. Type Definition Example of Use
Such systems may be
single-user (e.g. a personal
computer).
Multi-access on-line Any users linked by Holiday or airline booking
workstations to a central system. One person must
computer such as in a be locked out when another
network. is updating the file. This
helps to prevent Double
booking
Interactive processing The user has to be present Select from a menu at
and program cannot ATM.
proceed until there is
some input from the user
Distributed system Processing is carried out Databases e.g. libraries.
independently in more
than one location, but
with shared and
controlled access to some
common facilities.
Multiprogramming: Ability to run many Mainframe systems. Each
programs apparently at job is allocated a small
the same time. amount of processing time
(time slice) in turn.
Multi tasking The ability to hold several Usually uses GUI’s.
programs in RAM at one Facilitates import and
time but the user switches export of data.
between them.
Source: WJEC GCSE ICT INSET Document on paper 2. Cardiff. March 2003.