SAD

1. 1
Introduction to Information Technology – Notes on the SDLC (Dr R.K. Singla)
THE ROLE OF THE SYSTEMS ANALYST.
 To analyze business systems with problems and to design new or modify systems to solve the problems.
 To develop systems to meet new needs.
 To prepare and maintain manuals to communicate company policies and procedures.
 To design business forms for collecting and distributing information.
 To perform records management. (distribution and use of reports.)
 To participate in the selection of information processing equipment and to establish standards for
equipment selection.
 To prepare and maintain business organization charts.
Organization charts are a tool for the systems analyst to use to increase their knowledge of operational
processes, job responsibilities, and information flow.
OPPORTUNITIES FOR SYSTEMS ANALYSTS.
There are many requirements for systems analysts within companies. Even as users take over more
responsibility for their own programming, the systems analyst is still needed.
It is a highly paid position and a high position on an organization chart. The MIS department management
usually report to a V.P.
Qualifications.
 technical specialist
 a leader
 able to secure cooperation
 non-threatening to others - ie. human relations
 creative - designers
 good speaker and writer (good communication skills)
The analyst must be able to give good presentations to explain and sell ideas.
Background.
Bachelors or D.E.C + working experience.
Work experience is essential for on the job experience, expertise and management confidence.
Career Path vs Life Cycle
analysis design implementation operation
systems analyst increased
creativity
programmer/analyst
Salary
increased programmer
responsibility
technician
Life Cycle Phases

2. 2
SYSTEMS & SUB-SYSTEMS
A system is a combination of resources working together to convert input into output.
A business information system is a system that uses resources to convert data into information needed to
accomplish the purposes of a business.
Types of business information systems and sub-systems.
Accounting or Finance | Administration | Marketing
- General Ledger | - Payroll | - Sales
- Accounts Payable | - Personnel | - Inventory
- Accounts Receivable | - Pensions | - Distribution
More systems and sub-systems.
A business can be referred to as a system. Within a business there are several sub-systems. In a product-
oriented business the functional activities could be :
Purchasing - raw material from suppliers
Receiving - goods from suppliers
Inventory - storing
Production - designing and manufacturing
Sales - sales to customers
Distribution - of product
Billing - to customers
Collection - from customers
Disbursing - to suppliers
These activities are integrated through management and administration to make a "system of systems" to
meet its objectives and goals.
Product Flow
The physical flow of goods.
ex. raw materials go to assembly and then to finished goods.
Information flow
The flow of support documents through a system.
ex. purchase order prepared in Purchasing, sent to receiving, then to inventory ....
ex. payroll receives time cards then prepares paychecks
INFORMATION SYSTEM LEVELS.
Top Management - Strategic, goals, long-range planning, new products.
Middle Managment - Tactical - allocating and controlling resources, planning.
Lower Managment - Supervisory, short term, day to day scheduling.
Functional - the information for day to day operation.
A management information system spans at least on vertical level, and has feedback and control.
Feedback is comparing output to desired input.
Control is action taken to bring the difference within acceptable range.
THE SYSTEM DEVELOPMENT LIFE CYCLE
Life cycle of a Business Information System
a) Analysis Phase b) Design Phase c) Implementation Phase d) Operation Phase
As a system evolves through these phases there is both forward and backward movement.
Accompanying each phase are:
- performance of tasks - documentation - management reviews
As a result of the reviews, there is feedback where the system may not meet an objective. This will cause a
backward or cycling back of the system.
Systems analysis is the performance, management, and documentation of the activities related to the four
phases. A systems analyst is the individual responsible for the performance of the systems analysis.

3. 3
SUMMARY OF THE ACTIVIES IN EACH STEP OF THE LIFE CYCLE (SDLC)
The Analysis Phase.
 The problem is defined.
 Alternate solutions are studied.
 Recommendations are made to commit resources to the design of the system.
The Design Phase.
 A detail design of the system is accomplished.
 Technical specifications are prepared for equipment allocation, personnel, and computer programming.
The Implementation Phase.
 The computer-based system is constructed from the specifications.
 Procedures, manuals, software specifications, and other documentation is completed.
 Staff is trained.
 System is tested.
The Operation Phase.
 The new system is installed, operated, and maintained.
 The performance is reviewed.
 Changes are managed.
Each phase is documented and reviewed before moving forward. At each phase there can also be a step
back to repeat part or all of a preceding phase.
Reviews of the Life-Cycle Activities.
Management reviews may occur at any time during the life-cycle activities, however a major review at the
conclusion of each step is needed so that a phase can be considered complete. The reviews are an
interaction between the systems analyst and the user.
Decisions that may occur at any review are
- proceed to the next phase
- cancel project
- redo certain parts.
Each successful review is a renewal of management commitment to the project.
DOCUMENTATION.
It is not a task done to "wind-up" an activity.
It is the product and it is continuous and cumulative throughout the project.
The most essential documents are called the base-line specifications.
 Performance specification
 Design specification
 System specification.
It is the visible and measurable end product and is the key to the successful management of the life-cycle.

4. 4
The SDLC first step.
A problem or user need.
A written request originating from the user either on a memo or a standard document is received by the
MIS department. This request serves as an authorization for an initial investigation.
The manager initiating the request informs staff and superiors of the investigation and requests their
cooperation.
The result of the initial investigation or information gathering is a document which serves as the project
directive requesting approval for the system design. Other names for this document - business
specification, performance specification.
Steps involved in this analysis.
1) Define the problem.
2) Data collection - On the organization, the employees, the work, and the work environment.
Start with existing information - company library, existing systems documentation.
Interviews. - be prepared, write down objectives, make appointments, be punctual.
- avoid interruptions, be a good listener, understand what is said.
- be non-committal, take brief notes
Advantages - face to face, flexible, adaptive, informative.
Disadvantages - time-consuming.
Questionnaires. - Types- open, fill in blanks, multiple choice.
Advantage - Economical
Disadvantages - Difficult to prepare, not everyone responds, will results be reliable and valid?
Observation. - Study the flow of work through the office.
Experience needed to know when and what to look for, and to prepare data flow diagrams.
Advantages - highly valid, first hand information.
Disadvantage - inconvenient, certain tasks are not daily.
Research. - external – trade magazines, vendors.
3) Prepare report consisting of: Statement of scope and objectives,
data flow diagrams, identification of system inputs and outputs.
FEASIBILITY ANALYSIS
1) Technical Feasibility?
Can it be done with existing technology?
2) Economic Feasibility?
Will the cost be offset by the benefits?
3) Operational Feasibility?
Will it work in the organization?
Economic feasibility or cost justification. At what point will the system become profitable.
Methods. Break-even analysis and ROI - Return on Investment
Note: Economic feasibility cannot be the only factor in a feasibility study as many benefits are
intangible and hard to quantify.
TANGIBLE BENEFITS INTANGIBLE BENEFITS
Increased sales Improved customer goodwill
Reduced expenses Improved employee morale
Reduced credit losses Better decision making

5. 5
Steps in the Feasibility Analysis
1) Form the system team. Users, management, technical staff.
2) Develop overview flowcharts. DFD from initial investigation.
3) Determine candidate systems. Hardware, processing, software.
4) Eliminate obvious candidates which:
- are too costly
- overkill the task
- beyond the technical knowledge
of the company
5) Detail the remaining candidates.
Input, output, processing, and storage requirements, and constraints.
6) Identify criteria for evaluation.
Performance criteria:
-reliability, accuracy, control, growth, flexibility, response time, usability
Costs:
-equipment, training, development, operation
7) Use a matrix to evaluate candidates with respect to the criteria. Assign a weight to each criteria.
- Rate each candidate (1 to 5)
- Multiply by the weight
- Add the scores for each candidate
8) The analyst should look at the closest highest scores, select the "best" system, and prepare a
recommendation.
DESIGN PHASE
INPUT DESIGN
Equipment
KEY-ENTRY - keyboard
DOCUMENT SCANNERS
- OCR - optical character reader (grocery checkout - bar codes)
- MICR - magnetic ink character reader (bank cheques)
- OMR - optical mark reader (exam scoring)
APPLICATION DEPENDENT TERMINALS
- ATM - automated teller machines
OTHER
- voice - touch-screen - light-pen
Evaluation
EVALUATE USER - application dependent terminal for general public
EVALUATE APPLICATION - speed considerations, volume of data, accuracy, control
EVALUATE COST
SCREEN DESIGN
Design considerations
- sequence must match input form
- place related items together
- field length and format must be known (MM/DD/YY)
- be consistent with field identifiers, messages, screen headers, and footers
- place data in same location on similar screens
- do not overcrowd the screen
- for columns of data, note that the cursor usually moves from left to right before top to bottom
- left justify text and alphanumeric data, right justify numeric data, line-up the decimal points
FORMS DESIGN AND OUTPUT DESIGN

6. 6
FILE DESIGN or DATABASE DESIGN
Steps involved in file design:
1) Establish the application support files, adding any required intermediate files needed to pass data
between the processing steps. Establish controls - backup files.
For each file,
2) Specify the access method required for each processing step.
3) Specify the organization required.
4) Specify the equipment needed to store the file. (disk, tape)
5) Determine the contents.
6) Determine the size.
Characteristics evaluated during file design.
- processing method
- required response time
- activity rate (number of transactions per processing run)
- volatility (number of adds, deletions)
- backup requirements
- device capacity
- costs (storage, maintenance, processing)
Some design considerations for placement of elements within a file:
- group keys at the beginning
- group related items together
- group most frequently used elements at the beginning
Types of files:
MASTER FILES Basic information about identified entities. Fairly static.
TRANSACTION FILES Records of source transactions used to update master files.
REFERENCE FILES Constant data used in an application run.
Tables not coded in programs since they can require updates occasionally. Tax tables.
ARCHIVAL OR HISTORY FILES Files kept for statistical or research purposes.
Transaction files that have been processed.
BACKUP FILES Copies of master or transaction files for the purpose of recovering lost
or damaged files. Several generations may be kept.
TRANSACTION LOG FILES Electronic journals kept for an audit trail on on-line systems.
Used for recovery during an on-line update.
Access Methods
PHYSICAL SEQUENTIAL OR SERIAL
Records are read in the same order in which they were recorded.
LOGICAL SEQUENTIAL OR KEY SEQUENCE
Records are read in a logical order according to a key field.
DIRECT Records are accessed by a value or key.
File Organizations
SEQUENTIAL Records are written one after the other. The file must always be read in the same order
and always from the beginning. To update, a new file must be created.
INDEXED Records can be accessed both sequentially or randomly by a key. Index files are maintained
to support the random access.
DIRECT Records are stored and located according to an address calculated by a mathematical formula
applied to a key. Fastest access. Does not handle large quantities of additions and deletions well.
DBMS - DATA BASE MANAGEMENT SYSTEM A group of logically related files. A method used to
reduce redundant data between files and systems. Allows sequential and direct access.
Requires a data base administrator to control application usage of data, to synchronize backup
procedures and to maintain the data base. The design of a database includes data modeling
(normalization and entity-relationship diagrams).
EQUIPMENT SPECIFICATION

7. 7
DECISION TABLES
A decision table is a tabular representation of:
1) Conditions: factors to consider in making a decision.
2) Actions: steps to be taken when a certain combination of conditions exist.
3) Rules: specific combinations of conditions and the actions to be taken
DESIGN OF CONTROLS
System controls are defined as "a plan to ensure that only valid data is accepted and processed
completely and accurately."
Controls must be built into the system and become an integrated part of the design of the system.
Controls are needed to:
1) ensure accuracy of data and reports
2) ensure integrity of files
3) ensure confidentiality of data
4) prevent fraud.
Types of controls: Methods:
- access controls - passwords
- source document controls - prenumbering
- data entry controls - batch totals
- processing controls - edit programs
- output controls - balance totals
- file controls - backup files
- documentation controls - up-to-date documentation
- organizational controls - separate duties
The user has a major responsibility towards defining adequate controls. Walk-throughs provide an
effective means of evaluating controls. Controls must be documented in the design specifications for the
system.
STEPS INVOLVED IN THE IMPLEMENTATION PHASE
1) Implementation plan
-Formal test plan The formal test plan describes the stages of testing:
- program or module tests
- system test done in stages - sample data, test file, pilot test, simulated live test,
- user acceptance test
- Training plan An outline describing the methods for training users and operation staff.
- Conversion plan A plan describing the conversion requirements of the system
2) Equipment aquisition and installation.
- Site preparation, equipment installation, and hardware and software checking.
- The equipment availability and check must be done in time for system tests.
3) Computer program development
- Computer program design
- Coding and debugging
- Program tests
4) Reference manual preparation
- Programmer's manual, Operation's manual, User's manual
5) Personnel training
6) System tests
7) Conversion
8) System specification

8. 8
TEST LOG
PROGRAM: ________________
TEST OR | | EXPECTED | ACTUAL | DATE | DATE |
CONDITION | DATA | RESULTS | RESULTS | TESTED | CORRECTED|
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
------------- OR --------------
TEST LOG # ____
PROGRAM: ________________
TEST: _________________________________________
_________________________________________
ERROR: _________________________________________
_________________________________________
TESTED BY: _________________
----------------------------------------------------------------
CORRECTION: ____________________________________
____________________________________
____________________________________
DATE COMPLETED: _____________________ BY: _____________________
RE-TESTED ____________________ BY: _____________________

9. 9
CONVERSION
To implement a system there are different methods which are referred to as conversion methods. This is
the process of converting from the old system to the new system.
Conversion methods:
1) Parallel conversion. Both the new system and the old system are run in parallel. It is time
consuming, may require additional personnel or effort, is expensive, errors may be
difficult to detect, and may delay the adoption of the new system. It has the least risk.
2) Immediate cut-over Also known as crash conversion. The old system is no longer used and
the new system takes over. It is the most risky. May be used when other methods are
not possible, if the system is not critical, or if a fallback to another procedure is available.
Sometimes may be used because of user pressure.
3) Pilot conversion The new system is used for a select group of transactions (example: one
department or one product line) and the old system is used for the majority of the
transactions. The volume on the new system can then be increased.
4) Phased conversion The system is phased-in by running some programs in the new system
with the rest of the processing on the old system. Gradually all phases of the new
system are in place. (example: orders entered on the new system and the invoicing
done on the old system.)
MAINTAINANCE OF THE SYSTEM
Performance Review
Change Requests