Data Processing 2

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Data Processing


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A processing mode is the way in which

transactions are grouped and handled for

input to the central processor forcomputation or generation of reports and

outputs.


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Batch processing system

A technique in which a number of similar

items or transactions to be processed are

grouped (batched) for processing as asingle unit at predetermined times.


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A batch of transactions is accumulated,

batch total complied for it, the transactions

transcribed on floppy diskette or other media at regular intervals for a

predetermined period of time (say weekly,

monthly, daily, etc.) after which it is

processed to produce the desired output.


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Payroll.

Stores ledgers etc.


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Online processing

In an On-line-direct-access system, the

input data enters the system from the point

of origin and output is transmitted directlyback to the user.

This system implies direct communication

between the CPU and the user for both

input and output.


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Two essential requirements forOnline-

processing system:

Terminals located in various departments/locations of an organization, connected to,

and controlled by the main computer.


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Storage of records in such a way that the

computer directly accesses a particular

record by its identifying records key,

without having to search through a

sequence of records which is possible only

if records are stored on a direct-access

storage device like floppy disk/ hard disk.


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Apart from transaction processing and file

updating, inquires are also handled by the

Online-Processing System.


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Example:

A salesman wanting to know the availability of a

stock as desired by his customer whose

accounts are more than 3 months past due..

Further, online processing ensures that therecords are in updated status at any time where

as with batch processing it is say one week or

so.

But on-line processing is usually more costly.


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Online system applications:

Banking system:Banking system: Online systems are

being used to inform bank customers of

the status of their account in response to

an inquiry by accessing the relevant file

using an online terminal.


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Airline reservation system:Airline reservation system: which

receive requests from the terminals of

hundreds of travel agents about booking

seats on a particular flight on a particular

date.


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Stock exchanges:Stock exchanges: Terminals located in

major stock exchanges throughout the

country and the offices of participating

brokerage firms enable the speedy

processing of share dealings.


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Benefits provided by Online Systems

Information is centralized:

Dissemination of information:

Reduction in paper works:

Improved accuracy: As terminal messages are

checked for accuracy before being transmitted to

the computer by data validation programs, the

quality of information in a system increases asthe input errors are reduced and the information

is more reliable.


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Elimination of tedious tasks: Routine

clerical tasks are replaced by terminal

operations providing a greater degree of

job interest, operating efficiency and job

satisfaction.


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Real-time Systems

Real time refers to the technique ofupdating files with transaction dataimmediately after the event to which it

relates occurs.Real-time systems are on-line systems

with tighter constraints on response time.

In these systems the data is processedand results are generated fast enough toinfluence ongoing activity.


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Characteristics of real time systems include:

1. Only a small volume of data is processed at

any one time.

2. Turnaround is critical.

3. Processing efficiency is subordinate to

response need.

4. The system responds to and often controls itsenvironments and the processing keep pace

with external events.


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5. Fairly fast response time (is only a

fraction of a second), allowing two-way

communication, i.e. interaction between

the user and the central processor.

6. Decision to be made on the basis of the

latest information available from files

which are getting continuously updated.


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Applications of Real-time Systems

Enquires about customers account status

can be answered in seconds.

Credit appraisal can be carried outimmediately.


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Time-Sharing

Time-sharing is a term used to describe a

processing system with a number of

independent, relatively low-speed, on-line,

simultaneously, usable stations which are

geographically remote from the computer

and from each other.


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Each station provides direct access to the

central processor for obtaining instant

responses to the questions asked or

statements made in an interactive

conversational mode.


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The speed of the system and the use of

multiprogramming allow the central

processor to switch from one using station

to another and to do a part of each job in

the allocated time slice until the work is

completed.


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Multiprogramming Systems

A technique for handling two or more

independent programs simultaneously by

overlapping or interleaving their execution

or by loading them into primary storage

and executing their instructions

concurrently.


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Multiprocessing

Pertaining to the simultaneous execution

of two or more computer programs or

sequences of instructions by a computer

system.

Frequently refers to simultaneous

execution accomplished by the use of a

system with more than one centralprocessor.


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A hardware and software architecture

which allows more than one processor to

work on different parts of a program at the

same time.


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Applications of multiprocessing:

Where some jobs are too large for one

computer to process.

Where it is required to solve aconsiderable number of problems

simultaneously and very speedily.

Where a high degree of protection against

breakdown is required.


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Distributed Data processing system

Unlike centralized transaction processing

in which all components run on the same

computer, distributed transaction

processing is a system in which one or

more components run on separate

computers and communicate across a

network.


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It is a network of computer systems that

fully support the data processing needs of

one organization, interacting with each

other and a vast database through a larger

computer that oversees the entire network.


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The essential requisites for a system to

be described as distributed are :

Computer processing ability is situated at more

than one location.

This facility is applied to user-oriented tasks.

A data transmission facility to enable the

interconnection of the locations.

Some element of data handling at each location.

Certain common standard of the conduct ofoperations must be followed.

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Data Processing 2