enough to respond to multiple on-line stations operating simultaneously. Large
capacity, peripheral on-line storage units are required to store additional operating-
system elements, user data and programs. And data transmission facilities must be
provided to communicate with on-line terminals in the next room, the next block or
thousands of miles away. The added costs of on-line processing are offset by the
resultant savings from eliminating repetitive clerical work. Most new computers have
on-line capability. The applications that are more effective with on-line operations
include order entry, inventory control, billing and accounts receivable, as well as other
systems in which people are working and interacting with customers continuously during
the workday.
d. On-line vs. Batch Processing. Compared to on-line processing, batch
processing is much slower. A complete payroll, from balancing to preparation of
checks, can be done in 3 hours by batch processing methods. An on-line application,
which handles individual transactions, is measured in seconds. An inquiry as to the
availability of a seat on an airline flight can be completed in 2 seconds. There is a
fundamental trade-off between serial /sequential processing with magnetic tape and
direct on-line processing with magnetic disk. On-line processing provides extremely
fast access to relatively small amounts of data on a random basis. Batch processing
provides an efficient and economical way to process relatively large amounts of
information. Many contemporary applications have both batch and on-line processing
components.
Figure 3-4. On-line processing: individual changes to a record are made
as the input occurs.
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