CH / S6CS / Nov. 2001
Content of Information Processing
1. Characteristics of Information Systems
2. Systems Development
3. Application of Information Technology
4. Social Implication
Information Systems (Ch 16, 17 Ray Bradley; ch 35, 36, 37 C S French;
ch 4 Heathcote and Bond)
Role of computers in information system

All computers are capable of performing four general operations :
In an information system, data are input to the computer from a keyboard or other input
devices, manipulated or processed by the computer in a predetermined manner (data
processing programs), and some forms of output is produced. Some of the raw or processed
data may be stored on disk, magnetic tape, or other device, or used to update information
already held on one of these devices.

Reasons for increasing roles of computer in information system :

The five stages of Data Processing system:
Collection of Data
Preparation of Data
Input of Data
Process of Data
Output of Information
Business information system

In general, there are 3 levels in the hierarchy of a business organization.
i.
The strategic level: consisting of senior management responsible for long term planning
and policy making decision.
ii.
The tactical level: consisting of middle management in charge of one particular
department or area of the business such as Sales and Marketing, Accounting, or Production.
iii.
The operational level: consisting of the workforce who are taking sales orders, keeping
accounts making the product, and so on.
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
Each level needs information suited to their particular needs. Information system can be classified
into the following types:
i.
Operational system: It is designed to process data generated by the day to day business
transaction. E.g. accounting system, invoicing system, stock control system and order entry
system.
ii.
Management system: The computer’s ability to process large quantities of data
efficiently means that it can be used to produce useful information for management purposes.
Often the same data that is used as part of an operational system can be used to produce
management information.
iii.
Decision support system: It is a system designed to help someone reach a decision by
summarizing all the available relevant information, internal or external to the company, such
statistic of employee’s salary, current interest rates, the price of oil, etc. It usually includes
interactive supporting system such as query language and spreadsheet.
iv.
Expert systems: They are a special type of decision support system that emulates human
reasoning. It draws inferences from the rules and knowledge given by the user.
Methods of Processing (p. 250 – 261 C S French)
Real-time processing

It means that the computer has to keep pace with some external operation, processing the data that
it receives more or less instantaneously and producing immediate results. (real-time)

As used in different situations, real-time systems fall into one of the two categories:
i.
ii.
process control

This is the control of machinery or industrial processes by means of a computer.
Sensors
continuously monitor data such as temperature, pressure,
composition of substances and so on and the computer reacts accordingly.
b)
e.g. nuclear power situation, chemical plant, etc.
information storage and retrieval (‘Interactive processing’)
a)
A different type of real-time system is one in which a single user or a number of users
need to be able to make queries and update information held in a file.
b)
Often such systems will involve large shared databases held on mainframe computers, e.g.
airline reservation system.
On-line processing

This expression simply means that it is connected
to the computer and it
is therefore possible to access information held on the computer.

For real-time processing, the input must be on-line to the computer.

Some systems may permit a user to access information, but not to change it.
Batch processing

Computer applications use either interactive or batch processing methods to process data.
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
In batch processing, the data input will be stored first in backing store, e.g. disk or tape, for
processing later, in batch.

While data entry for interactive processing is necessarily on-line
, data entry for batch
processing is frequently
off-line . I.e. Data may be input to a computer other than the one
on which it will eventually be processed or using
disks
.

Procedures for data entry in batch processing:

i.
The documents are examined by a data control clerk.
ii.
The source documents are then counted into batches of, say 50 or 100 and each of them are
numbered on a header slip attached to the batch, which records the batch’s progress.
iii.
Control totals are calculated manually for the batch. Some of these totals are meaningful, e.g.
total payments for workers, but some are meaningless, namely hash totals, only for checking.
iv.
The batch of data is keyed in by a data preparation clerk and stored in backing store.
v.
The batch is then passed to another clerk who will key in the data again for verification.
vi.
The batch of data in the backing store is now ready to be validated.
vii.
After validation, if there are any errors, they will be printed on a validation report and the
incorrect records in the batch will be retrieved and rekeyed. Steps vi and vii will repeated until
no errors are found.
viii.
The valid data are now held on a transaction file for later actual processing.
Validation checks:
i.
Presence check. Check that all items of data are present.
ii.
Character count. Some items, e.g. telephone number, are of fixed length.
iii.
Picture check. Ensure that certain fields are in the correct format. (Letters or numbers)
iv.
Range check. Check that a field lies within a particular range.
v.
Check digit checks.
vi.
File lookup. If the validation program has access to
data can be validated by referencing to those files.
vii.
Batch header checks. Any control totals on the batch header which have been manually
calculated by the computer operator and the totals calculated by the computer are compared.
reference files
, then input
Combined interactive and batch processing

Some applications use both interactive and batch processing.

In the example of banking application:
Services for credit an account by ATM in some countries are interactive and each transaction is
stored in transaction files. At night, the data in the transaction files is confirmed and input to a
program that produces summary reports.
Distributed processing

Rather than using a large mainframe, several computers can be used around the organisation and in
each branch office, by connecting together in network.

A distributed processing system is a system in which a job is performed by a number of computers
that are linked through a communication network. The computers perform cooperatively such that
their combined work can contribute to a larger goal.
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
In the 1960s the trend was to have a centralized data processing department with a mainframe
computer in an organization.

However, the recent trend is that each branch or department in an organization having its own
processing power in the form of workstations attached to those of other department in a form of
local area network (LAN).

Employees through the company may have ‘dumb’ terminals on their desk, i.e. terminals consisting
of a VDU and keyboard only, from which they can enter data and run programs. These terminals
are all connected to the mainframe computer. Is this distributed or centralized computing?

What are the advantages of distributed processing as opposed to centralized processing? What are
the disadvantages?
Advantages:
Reduction in costs and delays in transmitting and processing data
Reduced load on the “host”
Better local control and service
Disadvantages:
Better central control and higher in security
Ensuring data consistency
System Development (p. 339 – 340 Ray Bradley, p. 423 – 425 C S French)
The systems Life Cycle



Project selection. One particular area of the business is selected initially for computerization, for
one or more of the following reasons:
i.
large volume of data require repetitive processing
ii.
there is a need for better access to up-to-date information
iii.
high clerical costs could be reduced by computerization
iv.
better service to customers could result
v.
more control over certain areas, e.g. customer accounts
Overview of the system life cycle
i.
Commercial information systems all share a common life cycle pattern.
ii.
After years, an information system developed may start to deteriorate or seen inadequate.
Thus the life cycle will be starts all over again.
The stages in systems development (system life cycle)
i.
Analysis. This stage includes problem definition, preliminary investigation. After these
tasks, it will be then determined whether the request justifies further detailed investigation
and analysis. Afterward, if a decision is made to proceed, the project enters the design
phase.
ii.
Design. This stage involves the tasks of designing the output, input, files, database if
applicable system controls and test plan.
iii.
Development.
INFORMATION SYSTEM
There are two aspects to development: program development and
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equipment acquisition. The stage also includes writing program specifications. Then the
program will be coded, tested and documented.
iv.
Implementation. The new system becomes operational. This phase requires careful
timing and the co-ordination and the training of all the user departments involved.
v.
Maintenance. This stage includes performance monitoring, modification if required,
errors correction and keeping up-to-date documentation.
System Analysis

System analysis includes the problem definition, feasibility study and detail investigation on the
system.

Problem Definition. Before any analysis work begins, the requirements of the new system are
written down as the terms of reference. The terms of reference may contain:

i.
Objectives: what the new system must achieve; e.g. cost deduction, better service, better
management information, etc.
ii.
Constraints: any restrictions on cost, equipment to be used, areas of business that should be
left unchanged, and so on.
iii.
Time-scale: when a solution is required.
iv.
Report or output.
v.
Problems that have been identified with the current system.
vi.
Suggested solution considered by management.
Feasibility study: It is an examination of the possible solutions to the problem and indeed
whether the problem can be solved at all. Even if a problem can be solved it may be so complex
and expensive that it is not feasible. There are 3 aspects  technical, social and economic.

i.
Technical feasibility  whether the proposed system will achieve its objectives: or simple the
question.
ii.
Social feasibility  the effect on employees and customers.
iii.
Economic feasibility  whether the new system will be cost effective.
Investigation. Once the decision has been made to go ahead with a system, a complete
understanding of the existing system should be known. It will cover the data , the procedures , the
future , the management reports and the problem with the existing system.

Methods of fact finding :
Interviewing, questionnaires, observation, record inspection, user workshops
General System Analysis method

Systems Flowcharts (p. 341 – 342 Ray Bradley)
i.
Frequently a pictorial representation of how the system will work is easier to understand and
take in than a length text.
Manual Operation
Represent manual performance
e.g. collect application forms
INFORMATION SYSTEM
Process
Main process of the system
e.g. computer programs
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Manual Input
Key in information into the system
e.g. job of data entry clerks
Magnetic Disk
Random access data storage
e.g. database in harddisks
Punch Card
Old media for data input and
output e.g. time cards
Magnetic Tape
Sequential access data storage
e.g. data backup in tapes
Merge
Combine sets of data into one
e.g. relate two database into one
Report / Document
Hardcopy paper output
e.g. bank statement
Display Unit
Media for displaying information
e.g. VDU
Communication Link
Transmission of data with outside world
e.g. satellite communication
Sort
Sort a set of data
ii.
iii.
A system flowchart is a diagram and overview of a complete system. It will show:
a)
the tasks to be carried out in the new systems, whether manual or by the computer
b)
the devices (disk drives, tape drives, terminal, etc.) that are to be used in the system
c)
the media used for input, storage and output
d)
the files used by the system.
Exercises: Match following descriptions with the corresponding systems flowcharts below.
(1) A sequential payroll master file held on tape is updated form a sequential transaction
file using the ‘Grandfather-father-son’ method of update, and pay-slips are produced. B
(2) A transaction file held on tape is sorted on to a disk file, and a report produced in the
new sequence. F
(3) A collection of input documents is batched, and the batches keyed in and stored on
disk. E
(4) A transaction file held on tape is validated, with valid transactions being copied to a
disk file and an error report produced which gives details of invalid transaction. A
(5) A customer order is keyed in and the stock master file checked to as certain whether
sufficient stock is available. The customer order is stored on an indexed customer order
file. D
(6) Electricity bill payments are read by an OCR device and stored on disk. These
transaction are then used to update the indexed customer master file. C
A.
INFORMATION SYSTEM
B.
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C.
D.
E.
iv.
F.
Example 1. A library has the following check out procedure: A person wants to borrow a
book and takes the book to a check out counter. He gives the librarian the borrowing card and
the book. The librarian uses bar code reader to get both information of the borrower and the
book from the related database. If there is no error, it stores relevant information to a
transaction file of the borrowed books. The due date notice is then printed for the borrower.
If error occurs, an error report is generated for the librarian.
Simplify the above text into a system flowchart.
General Approach
a)
Always bear in mind that a system flowchart shows what the system would do, not how
the system works.
b)
So ignore any unimportant information which does not involve of data flow. E.g. The
sentence ‘A person wants to ... counter.’
c)
Convert the main data process into relevant system flowchart symbols.
d)
Name the symbols but don’t be too detailed. e.g. Don’t specify which hardware or
software are using or who does the specific jobs.
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e)
Join the symbols with arrows which represent the flow of data.
f)
Condition cannot be represented in a system flowchart. Therefore, just show what the
system would produce. Don’t label the data flow arrows with ‘Yes’, ‘‘No’
g)
No looping should be in a system flowchart. i.e. no cycle of data flow could be found.
Wants to
System flowchart
for example 1:
Collecta
borrow
borrowing
User
bar code
book
information
reader
to input
information
Book’s
database
Validate Borrower’s
Error
borrowing
report database
information
Borrowed
Perform
books
check-out
Due date
transaction
notice
Example 2. ABC College records the examination results of the students as follows: After
all examination papers are marked by the teachers, the secretary input the information into
the exam results database. Before updating the database, the system will automatically check
for any abnormal input. If these input is found, the system will alert the secretary to confirm
update or not.
v.
Simplify the above text into a system flowchart.
System flowchart for example 2:
vi.
Factors affecting the systems flowchart design:
a)
Is this batch or real-time system?
b)
How is the data to captured and input to the system?
c)
What file organization is therefore appropriate?
d)
What kind of storage media will be used?
e)
What will be the output from the system?
f)
What are the processing steps to be carried out?
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
Data Flow Diagram (p. 307 – 309 Ray Bradley)
i.
It shows how the data moves through the system, and what data stores are used. It does not
define what type of data storage is used.
Entity - data source or data destination  people who receive data or
output information
Process - an operation performed on the data. The two lines are optional;
the top section of the box can be used to label the process, the middle to
give a brief explanation, and the bottom to say where the process takes
place.
Data store - this could, for example, represent a file held on disk or
magnetic tape, a batch of input documents or a report.
Data flow - the arrow represents move of data between entities, processes or
data stores. The arrow should be labeled to describe what data is
involved.
User provides
Data to process
Stock number
User
Stock report
request
Description of stock
User receives data
from stock inquiry
Stock report request
Stock description data
Validation
Process
Stock number
Valid
stock data
Stock file
processing
Stock
description
User
Description of stock report
Select report
output format
Output formatting data
ii.
The processing elements from one diagram may be decomposed so that further basic symbols
are used, and the amount of detail becomes more and more comprehensive as you delve deeper
into the system.
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iii.
The simplest of data flow diagram might consist of a query from the user of a stock control
system. The user provides the stock number and the result of the processing might be
information regarding ‘a description and level of the stock’. The idea is shown in fig. 3(a),
and the processing can easily be developed into a further data flow diagram shown in fig. 3(b).
iv.
Another DFD example. Suppose that we wish to analyze what happens in an office where
Sue, the accounts clerk, processes requests for the payment of expenses in a company.
A typical scenario would be that an employee brings along a filled-in expenses sheet, then Sue
verifies the signature, transfers the information into the computer system, and makes sure that a
particular budget is not over spent. If successful, then a cheque must be raised, signed by the
chief accountant, then put in a tray ready for collection via Sue.
The following data flow diagram illustrates the typical transactions.
Process
forms
Expenses
Forms
Unprocessed
forms
Balance
verified
Expenses
Forms
Sue
checks
signatures
Employee
signature
rejected
Rejected
forms
Awaiting
collection
Happy
Employee
Sue
signed
cheque
identity

Processed
verified
employee
Balance
Rejected
forms
Sue
Signature
verified
Rejected
forms
checks
balance
Insufficient
funds
Sue
states
reasons for
rejection
Balance
verified
Awaiting
signature
Happy
Employee
cheques
Rejected
forms
Accounts
Unsigned
cheques
Sue
prepares
cheques
Unsigned
cheques
Chief
cheques
account
signs
Critical path analysis (p. 313 - 315 Ray Bradley)
i.
It is a branch of operation research, i.e. the use of mathematical and scientific methods in the
management decision-making role in modern industry.
ii.
The analysis basically divides up a project into smaller self-contained activities (each of which
may be further subdivided) and assigns the time and resources that are necessary to complete
each activity.
iii.
Then the project as a whole is represented by special graphs. Fig. 5 shows a simple example
on preparing and cooking a meal.
iv.
The numbers in fig. 5 are known as nodes . We can now construct what is called a network
using the nodes to represent the
events and branches to represent activities
, as
shown in fig. 6.
v.
From the graphs, by analyzing the times through the various paths, the longest time from the
start to the finish of the project may be determined, and the path with the longest time is known
as the critical path
. The critical path would then determine the length of time
that would needed to complete the entire project.
vi.
If the project was to be completed in a shorter time, some of the times on this critical path must
be cut down.
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Prepare
Fillet (a)
2
Fry fillet
3
until brown
Mix paté until
smooth
Roast
fillet
4
Leave until
cold
13
Prepare
fillet (b)
5
Prepare and
roll out pastry
14
6
Bake in oven until done
15
1
Prepare broccoli
7
Cook broccoli
Prepare carrots
8
Cook carrots
Prepare asparagus
9
Cook asparagus
Prepare gravy
10
Cook gravy
Prepare roast
5m
2
11
5m
Part boil
3
10 m
12
4
Serve 16
dinner
Roast potatoes
30 m
13
10 m
2m
5
14
7m
6
40 m
15
1
3m
2m
7
10 m
3m
8
20 m
2m
9
15 m
2m
10
3m
11
10 m
12
3m  16
50 m
vii.
If this is done, then a new critical path may be created.
viii.
The above techniques are also known as
Review Technicque
.
ix.
The critical path from the fig. 5 is the route through the network that takes the longest amount
of time, as this will be the shortest time to complete the project. From fig. 5 the times for each
activity into account then the time through each path can be found as follows:
x.
From the following diagram it can be seen that the critical path is 1 – 2 – 3 – 4 – 13 – 14 –
15 – 16
.
PERT
,
Program
Evaluation
and
Total time of 1st path = 5 + 5 + 10 + 30 + 10 + 40 + 3 = 103 minutes
Total time of 2nd path = 2 + 0 + 10 + 40 + 3 = 55 minutes
Total time of 3rd path = 7 + 0 + 10 + 40 + 3 = 60 minutes
Total time of 4th path = 2 + 10 + 3 = 15 minutes
Total time of 5th path = 3 + 20 + 3 = 26 minutes
Total time of 6th path = 2 + 15 + 3 = 20 minutes
Total time of 7th path = 2 + 3 + 3 = 8 minutes
Total time of 8th path = 3 + 10 + 50 + 3 = 66 minutes

HIPO Diagram (Hierarchy-Input/Process/Output Diagram) (p. 307 Ray Bradley)
i.
The disadvantage of flowcharts is that they depict sequential and linear systems very well, but
not necessarily the more complex, even parallel, procedures that can be constructed in
computing.
ii.
In order to make programming a more organized and structured activity rather than an
inductive one detailed, HIPO diagrams were introduced. (Example shown in fig. 7.)
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iii.
The intention is to demonstrate the relationships between input and process, and process and
output rather than emphasize on the structure of the system.
HIERARCHY DIAGRAM
1.0
3.0
2.0
2.1
3.1
4.0
3.2
5.0
4.1
4.2
Legend
Description
Section
OVERVIEW DIAGRAM
4.2
Process
5.2
5.3
1
2
3
4
5
DETAIL DIAGRAM
3.0
Input
5.1
Output
From 4.1
Input
1.
1.
2.
2.
Process
3.
3.
4.
4.
Output
5.
To 5.1

Decision Table (p. 310 – 313 Ray Bradley)
i.
The decision tables show the content of decisions, combinations of conditions and
combinations of actions.
ii.
A decision table consists of the condition stub, the condition entry, the action stub and the
action entry. In the decision table these four elements form quadrants, thus
:
condition stub
:
:
action stub
:
iii.
:
condition entries
:
:
action entries
:
The condition entries’ and action entries’ quadrants together constitute one or more decision
rules, which run vertically through the two quadrants. These rules indicate the actions that are
to be taken according to particular combinations of conditions. (Example shown in fig. 8)
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Figure 8 Decision table with four redundancies
Ordering Procedure
1
2
4
5
7
9
10
12
13
A. Customer wholesale?
B. Qty. sufficient at East Coast?
C. Qty. sufficient at West Coast?
D. Call from East Coast?
Y
Y

Y
Y

Y
N
Y
Y
N
N
Y
N
Y
Y

N
N

N
Y

Y
N

Y
N
N
Y
N
N
N
N
Y
Y
E. Ship from West Coast
F. Ship from East Coast
G. Bill at wholesale price
H. Bill at retail price
I. Backorder
.
X
X
.
.
X
.
X
.
.
.
X
X
.
.
X
.
X
.
.
.
.
.
.
X
.
X
.
X
.
X
.
.
X
.
.
X
.
X
.
X
.
.
X
.
System Design (p. 427 – 430 C S French)

The design of a new system can be conveniently divided into following elements:
outputs, inputs, files or database component and procedures and programs.

Outputs. It is necessary to consider what is required from the system before deciding how to set
about producing it. It is necessary to consider content , format
, sequence
,
output
of reports and document and output media
.

Inputs consideration includes:


i.
Data collection methods and validation
ii.
Types of input media available
iii.
Volumes of input documents
iv.
Design of input layouts
File and database components consideration includes:
i.
Storage media
ii.
Method of file organisation and access
iii.
File security
iv.
Record layouts
Procedure and programs involves both computer and clerical procedures.
Forms design (p. 442 – 443 C S French)

The completion of a form may be the first operation of a procedure, a by-product of an operation
within a procedure, the end product of a procedure, or the form may be completed at various stages
with a procedure.

Aim. To keep forms to the minimum consistent with serving the needs of the system.

Features of design. (ref.)
i.
Size of forms.
ii.
Types of paper. Consideration should be given to frequency of handling storage needs
conditions under which forms are completed and prestige requirements, etc.
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iii.
Identification. Self-explanatory title; different colours or bold symbols for copies; serial
numbers for internal check.
iv.
Common information. If two forms are used in conjunction with each other, the common
information should be in the same sequence and position.
v.
Vertical spacing. Adequate space for each time of entry.
vi.
Columns. The length of column heading should be tailored to the width pre-printed, leaving
only information to be entered in the column.
vii.
Pre-printing. As much as possible of the column detail should be pre-printed, leaving only
variable data to be entered.
viii.
Clarity. Overall simplicity and logical sequence for completion.
ix.
Miscellaneous. Pre-punched holes for sub-sequence filing.
x.
Multi-part sets. Carrying the image through all copies necessary, e.g. carbon, no-carbonrequired paper, carbon patches, etc.
*** Internal check
i.
Definition. The arrangement of procedure and systems, and the allocation of duties so that
there is an automatic check on what is being done.
** A Principle. No one person should be placed in the position of having responsibility for all aspects
of a business transaction.
ii.
Purpose achieved.
reduce the possibility of errors
determine the responsibility of errors
assist supervision
reduce the work of internal and external auditors
iii.
e.g. serial numbers on forms, requirements for two signatures on cheques.
User interface (Ref.)

The interaction between end-users and the computer is said to take place at the man-machine
interface or the “Human Computer Interface” (HCI).

The primary purpose of the HCI is to enable communication to and fro between the user and the
computer, i.e. to make the computer easier to be used.

One of the most important features normally required in an HCI is that it should be “User
Friendly”. However what makes an HCI user friendly?
i.
easier for user to start using the system
ii.
self-contained
iii.
reduce the effort and information of user
iv.
insulate users from unexpected or false system actions
v.
allow adjustment to different levels
vi.
make the user feel in control of what is going on
vii.
enable the user to reason about what is going on.
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
Types of interface
i.
ii.
Command Driven Interface
a)
User can interact with the computer directly by the use of commands.
b)
Advantage. Enable the experienced user quickly and simply to instruct the computer
what to do.
c)
Disadvantage. Require the user to already have knowledge of what commands are
available what they do and the rules governing how they should be typed. (syntax)
d)
E.g. DOS commands
FoxPro.
(such as DIR/W), dot commands in dBase IV, commands in
Menu Driven Interface
a)
b)
The simplest menu provides the user with a number of options and a simple means of
selecting between them as shown in fig. 9.
Alternative methods of screen activation  typing a single or a combination of keystroke
(e.g. Shift-F5) or moving cursor or mouse pointer to suitable type <Enter> or click mouse
button.
c)
After the screen activation, the corresponding action will follow, or a lower level menu
will be invoked.
d)
Pull-down menu. A special type of menu used in WINDOWing. As the names suggest
these menus are made to appear above or below an item on the screen in order to accept a
choice from the user.
****************************************************
MENU
****************************************************
1.
USER
2.
HKULOGO
****************************************************
ENTER CHOICE >
iii.
fig. 9
User Interface Management System (UIMS)
a)
The aims of UIMS is the creation of a means by which a consistent interface with the
same “look and feel” can be provided for any number of different applications within the
same system.
b)
It provides
standard facilities for handling the user dialogue,
standard software for managing application programs,
standard rule governing the way in which various features should appear or behave,
e.g. the use of single-click and double-click in MS Windows environment. (singleclick : select, double-click : activate or restore window)
iv.
Special-purpose HCI. There are two main types:
a)
A part of HCI provided by special hardware and software, industrial process monitoring.
b)
Embedded inside some special-purpose equipment, e.g. interface on a digital watch, ATM
machine.
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Some Criteria for Design

Economical. The costs and benefits of the new system comparing with the old one.

Work flows. Including methods of transmitting data to or from the computer, file organization,
etc.

Specialization, Simplification and Standardization (Three Ss).

Flexibility.
i.
Integration of procedures.
integration possible.
The centralized nature of computer processing makes the
ii.
Modularity of hardware. Choose the hardware to ensure that it is capable of being expanded.
iii.
Peak periods / treatment of exceptions. Design the system to cope with peak period
processing and exceptional items, possibly dealing with separate modules.
** Exception principle. Only deviations from plan are reported for management’s attention.

Reliability. Maintenance requirements, the expected life of the hardware and the backup facilities
(in case of breakdown) must be considered.

Forms. Data must be presented to the computer in a machine-sensible form. Thus,
i.
input forms are designed to reduce the steps necessary between origination of data and its
input.
ii.
output forms are designed to be in a humanly legible.

Existing system. Consideration must be given to the existing staff, procedures, equipment, forms,
etc., in the design of any new system.

Continuous control. Great need for care in internal check as the majority of steps are carried out
automatically.

Time. Speeds of equipment, modes of access and processing methods.
System Specification (p. 430 - 431 C. S. French)

The detailed documentation of the proposed new system.
communication and record.

Note that different persons are required to know only parts of the whole specification.

Contents.
It serves two main purposes:
i.
Preliminary information. Contents, lists names of ordinary users and authorized users.
ii.
Objectives of the system. Aims and benefits arising from implementation.
iii.
System description. Details of all procedures both clerical and computer.
iv.
Detailed specification. Details of input files, output files and master files with their sample
layouts; and details of source document, output documents, screen layouts and HCI designs,
etc.
v.
Program specification, including:
a)
Detail input, output and processes of each program run.
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b)
Test data.
c)
Stop / start, file-checking and error-checking procedures.
d)
Controls.
e)
Relationship between procedures and computer runs.
vi.
Implementation procedures. Details of timetable, conversion procedures and change-over
procedures.
vii.
Equipment.
viii.
User-department instructions for input to and output from the system.
System Development

Two main tasks here: program development and equipment acquisition.
Program Development

The programmer needs to know exactly what the program is required to do and normally works
from a program specification, a document from the system specification introduced in last section.

The program specification define the input, processing and outputs required. Then the program
development cycles starts.

Prototyping. (p.440 C. S. French) means building a working model of a new system in order to
evaluate it, test or have it approved before building the final product. There are three activities
described as of prototyping:

i.
Mock-ups
. It has the appearance of the final system but lacks any real processing.
ii.
Trial Prototyping
.
It is a simplified working model of a proposed system or
subsystem, may be of user interface, or processing. Normally it is thrown
away at the
end of the prototyping exercise.
iii.
Rapid Prototyping
. A simplified version of the system is build and then reviewed.
Following the review the prototype is extended
and upgraded
to become
version one of the new system.
System Testing. (p.84 Heathcote and Bond) It is to ensure both that the individual programs
have been written correctly and the system as a whole will work, i.e. the link between the programs
in a suite. It include two kinds of test:
i.
Function testing. The system is tested to make sure all parts of it work correctly using test
data.
ii.
Recovery testing. Tests are carried out to ensure that the system can recover from various
types of failure including hardware failures or power failures.
iii.
Performance testing. This carried out to ensure that the system performs satisfactorily with a
realistic volume of data, in conditions which will prevail in the user environment.
** It is important to notice that the independent test data should be designed by
ones
other
than programmers
. The analysis in conjunction with the user department should do this job.
This will ensure that every case eventually is designed into the test data pack and thus the programs
are subjected to the most harsh examination.
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Documentation

Aims:
To help in the design of the system by working a set of standards and having available a clear
description of the work down so far.
i.

ii.
To ensure that everyone involved in the system fully understands how their aspect of the
system will work.
iii.
To ensure that the system can be maintained after completion of the system.
Contents of a documented system:
i.
An accurate and up-to-date systems specification.
ii.
Systems flowcharts or data flow diagrams.
iii.
A structure diagram, flowchart or pseudocode for each program.
iv.
Organization, contents and layout of each file used.
v.
Layout and contents of all output prints and displays.
vi.
Current version of each program listing.
vii.
Test data and expected results.
In some system, these contents may be combined as the technical documentation.

Addition items of the documentation.
i.
A Clerical Procedures Manual. This details the activities that clerical staff will undertake in
preparing data for input to the system, and the action required to be taken when errors occur.
ii.
Operation instructions include
details of the procedure for starting the program
details of disks or tapes required
special stationary to be used
the number of copies of each report, and who is to receive the output
backup procedures to be followed
recovery procedure in the event of hardware failure.
iii.
Data preparation instructions contain the instruction on data entry and description on how
each field should be entered.
Note that these three manuals may be combined as the user documentation or user manual.
Resource Planning and Equipment Acquisition (p. 551-552 C. S. French)

Before a new system can be put into operation, any new hardware will have to be installed. A great
deal of detailed planning and preparation now needs to be done in order that the installation of the
machine and changeover to the computer-based system are achieved smoothly and efficiently.

There is planning that is required up to the time of delivery of the machine landed and then on to
the time that the system is operational. It is normally so involved that it needs to be planned out
using a chart that shows the “Network” of related activities and events that must take place and
their interdependencies. Thus estimation of time taken to complete tasks is very important.

Main resources concerned:
Site
Building
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Environment: humidity, dust control, etc.
Standby equipment
Staff: selection and training
Finance

Installation of Computer. It is responsible of the manufacturer’s engineers in conjunction with the
computer manager or his representative. The machine is tested from an engineering point of view
and handed over.
System Implementation

Implementation, following the development stage, this involve the co-ordination of the efforts of
the user department and the data processing department in getting the new system into operation.
In this stage, the system is already developed and now starting to be used.

The major activities in this stage include:
Training of staff
Data conversion or more specific, master file conversion
Changeover procedures

Training of staff (p. 445 C. S. French)
i.
The amount of training required for various categories of personnel will depend upon the
complexity of the system and the skills presently available.
ii.
The following aids would be used, as appropriate:
Handbook. produced as a development from the systems specification.
Courses. run by the computer manufacturers.
Lectures.

Master File Conversion (p. 446 C. S. French)
i.
The existing data, or master files, may be of paper form, and thus it is necessary to convert
them into a magnetic form. Generally, the processes include the following stages:
a)
Production of control totals by adding machine.
b)
Transcription of the available data to a special input document designed for ease of data
entry.
c)
Insertion of all new data required onto input document.
d)
Transcription of data form documents to magnetic media.
e)
Verification of transcribed data.
f)
File-creation run. A special written computer program produces the master records in
the required format in magnetic storage.
g)
Printing out of files for comparison with old files.
h)
Printing out of control totals for agreement with pre-lists.
i)
At a data immediately prior to changeover, variable data is inserted in master files.
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
Changeover Procedure (p.446 C. S. French)
Three basic methods: direct, parallel and pilot
i.
Parallel
a)
The old and new systems are run
concurrently
, using the same inputs.
b)
The outputs are compared and reasons for differences are resolved. Output from the old
system continues to be distributed until the new system has proved satisfactory.
ii.
Direct. The old system is stopped
immediately.
altogether and the new system becomes operational
iii.
Pilot. The whole system is break down into modules. Each module would be changed over by
one of the above two methods.
System Maintenance (p.447 C. S. French)

Once a system implemented and in full operation, it is kept to be effective and efficient
(maintenance) and examined to see if it has met the objectives set out in the original specification
(evaluation).

The need of effort in maintenance:
i.
Unforeseen problems may need to be overcome and that may involve returning to earlier
stages in the development cycle to take corrective action.
ii.
From time to time the requirements of the organization will change and the system will have
to be examined to see if it can cope with the changes.
** It should be appreciated that maintenance of the system should be considered at the analysis and
design stage so that any software written should be done in the most general way possible, so that
modification at a later stage can be more efficiently carried out.

Evaluation.
i.
It is essential that each module of the system is exhaustively tested to prove that a program is
absolute correct under all conditions. As a whole, it is crucial to test whether the fundamental
objectives mentioned at the beginning of this section have been achieved.
ii.
The reasons for reviewed periodically:
To deal with unforeseen problems.
To confirm that the plan objectives are being met.
To ensure that the system is able to cope with changing requirements of business.
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