Modes of Operations
• On-line versus Off-line
• Batch Processing
• Real-time Processing
• Comparison between Batch
Processing & Real-time Processing
• Time Sharing
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Modes of Operations
• the ways of using computers
• the ‘best’ mode depends on the type of application
• three most common processing methods:
–
–
–
–
–
batch processing
real-time processing
interactive
Multitasking
Time sharing / multi-user system
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On-line versus Off-line
• On-line
– relates to data and/or hardware devices
• accessible to
• under the control of a computer system
– usually interactive
• Off-line
– relates to data and/or hardware devices
• not accessible to
• not under the control of a computer system
[refer to Fig 7.1 & 2] 3
Batch Processing
• a technique where transactions are collected into
groups (batches) over a period of time and processed
together
• is often used in data processing
• where it is not economical to process the data at the
same time as they are received
• Examples
– a payroll system
– processing examination records
[refer to Fig 7.3 & 4]
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Real-time Processing
• the processing of events as data are
received, usually in a continuous feedback
loop
• where there are situations that require
immediate data processing
• entire procedure: on-line
• no delay
• more expensive than batch processing
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Examples of real-time processing
• the reactor temperature maintaining system
in a nuclear power station
• reservations systems
–
–
–
–
booking cinema ticket
reserving a hotel room
reserving an airline ticket
military systems
• air traffic control systems
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Comparison between the Two
Batch
processing
Real-time
processing
time delay % data
collection &
processing
the computer is only
used for a short time
no time delay
continually on-line
immediate response
the computer is
continually occupied
Investment Cost
little in software &
hardware
can be very
expensive in both
Mode of Access
sequential access
direct access
Time Delay
Computer Time
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Time Sharing
• is when multiple end-uses share time on a
single computer in an on-line environment
• computers work much faster than their input
and output devices
• each user is given a time slice of CPU time
• examples
– bank’s cashcard system
– a university campus
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