This document defines and describes different types of computer systems including batch processing systems, single-user systems, multi-user systems, single-tasking, multi-tasking, multiprogramming, and distributed systems. Batch processing involves submitting jobs to a queue to be processed without interaction, such as overnight. Single-user systems are used by only one person at a time while multi-user systems allow multiple users to connect simultaneously. Multi-tasking runs multiple applications at once, multiprogramming runs multiple jobs in memory simultaneously by allocating CPU time slices.

1. batch, single user, multi-user (multi-access), single-
tasking, multi-tasking, multiprogramming, stand-alone
and distributed systems

2. Batch
 One or more programs (together with
any data needed) are submitted to the
computer as a 'job' and put in
a queue to await processing.
 There is no interaction between user
and computer.
 Processing can be done at off-peak
times such as overnight, as no
interaction is needed

3. Examples
 A payroll run for a company.
 Gas and Electricity bills are produced
using a batch processing system.

4. How does a payroll work?
 Each month time sheets and pay
information (hours worked, overtime etc)
are collected together to be processed
as a single batch.
 The batch process is carried out with no
user interaction and may be done
overnight, when demand for the
computer’s resources is lower.
 Errors are stored in a file for later use
and are not dealt with as they occur.

5. How does a utility bill system
work?
 Customer’s electricity or gas meter
readings are collected together to be
processed in a batch.
 The batch process is carried out with no
user interaction and may be done
overnight, when demand for the
computer’s resources is lower.
 Errors are stored in a file for later use
and are not dealt with as they occur.

6. Single user (stand alone)
 A system which is used by a single
person at any one time, i.e. the entire
information on the hard disk used by
only one person is called single user
system.
 This system is not connected to a
network so cannot communicate to other
users.

7. Multi- user, multi access
 A number of individual users are connected
to a central computer and appear to have
control. This is not the same as a network.
 The processor gives a time slice to each
terminal and, during that time
allocation, processing that is needed is
carried out. By rotating around the
terminals on the system and processing in
short bursts, each user has the impression
that they are the sole users of the system.

8. Multi tasking
 Multiple applications are able to be run
at the same time by the processor.
Usually refers to a PC.
 A number of tasks are loaded and
processed in turn for short time-slices
until completed. It appears that the
computer is running several applications
at the same time..

9. Multiprogramming
 A multiprogramming system is one
where more than one job is held in
computer’s main memory at the same
time and can be processed by the
computer’s CPU at (apparently) the
same time.
 Multiprogramming is used to ensure the
most efficient use of the CPU and
prevent it from being idle while waiting
for a slower peripheral.

10. How does multiprogramming
work?
The operating system may move jobs in
and out of memory and allows each job
a predetermined time slice to access the
CPU. This process is called scheduling
and is controlled by a scheduler
program.

11. Tasks
 Complete the worksheet using the
Theory notes on the Teach-ICT.com
website.
 Link in shared area A2 Comp >
Hardware > Theory >Networks Theory
 http://www.teach-
ict.com/as_as_computing/ocr/H447/F45
3/3_3_1/features_of_os/miniweb/index.h
tm