Types of Changeover strategies/Ways of implementing a new system
a) Direct changeover (straight)
It is where the new system is implemented fully and the old one discarded (abandoned)
immediately. This strategy demands thorough testing and well-planned fil
System design (construction)
This is the most crucial stage in which the requirements
specifications are converted into the logical and Physical
(detailed) view of the system.
The system analyst uses the requirement specification documents
to create a sys
Principles of System Development
Get the system users involved.
Use a problem-solving approach.
Establish phases and activities.
Document through development.
Manage the process and projects
Justify systems as capital investmen
Essential phases of system development.
1. Scope Definition
Problem statement a statement and categorization of problems, opportunities, and directives;
may also include constraints and an initial vision for the solution. Synonyms include preliminary
CHARACTERISTICS OF SYSTEMS
Holistic thinking- A system is considered as a whole.
The components that make up a system may be simple but their
combination creates a complex whole whose overall performance
(goals) are more sophisticated than those of the i
Automated tools for system development.
General: There can be multiple strategies or routes through the traditional phases.
Thus, one size does not fit all projects.
We have included a few of the more common routes, but there are literally dozens of
TYPES OF PROCESSORS
Processors are classified based on:
Intel Corporation is a company that specializes in manufacturing
In 1971, it combined the ALU and CU on a single tiny semi
A. Automated methods
Used when actual data is required but difficult to use interviews,
observation and questionnaires.
Involves use of devices that capture data from source e.g. video
Is a specification requirement spec
The main memory / primary memory.
Is the storage location of data and instructions accessed by the control
- The main memory forms the basis of processing all data to be processed
and the instructions to be executed by the computer must first be st
CLASSIFICATION OFA SYSTEM
Systems can be divided into:
a) Deterministic; are systems whose outputs are known
precisely by their input. They function according to some
predefined procedures and hence their future behavior can
be predicted accurately e.g. a
Are peripheral devices that the computer uses to give out information after the
Information is given out a softcopy or hardcopy.
It is the tangible output.
Information is recorded on a physical medium e.g
2. Pointing devices
These are input devices that enter data or instructions into the computer
by controlling the pointer on the screen.
- Mostly used with computers having the Graphical User Interface (GUI)
operating system like Windows.
i) A MOUSE
NON IMPACT PRINTERS
The printing head element does not come into contact with the stationary
but by other means like thermal (heat) and pressure.
Non-impact printers are usually quieter, costly and faster in printing.
Examples: Laser Printers, Inkjet prin
CHARACTERISTICS OF A SUCCESSFUL SYSTEM
Should achieve the goals set for it e.g. operational goals
concerned with performance and system goals concerned
Should fit the structure of the business for which it was developed and b
Cross Life-Cycle Activities
Cross life-cycle activity any activity that overlaps many or all phases of the systems
Fact-finding - the formal process of using research, interviews, meetings, questionnaires,
THEORIES OF SYSTEM DEVELOPMENT
These theories are a timed at identifying business requirements
and hence develop information systems that meet them.
a) Traditional approach: relies mostly on the skills and
experience of individual staff members to carry o
FACTORS TO CONSIDER WHEN CHOOSING AN OPERATING SYSTEM
When selecting an operating system for a computer, the following factors may be considered:
1. The hardware configuration of a computer e.g. memory capacity, processor speed and
hard disk capacity.
It is the putting the system into real use. It involves installing the system in the user's computers,
testing the installed system, converting from the old system to the new one and training the users.
System implementation involves
QUESTIONS ON SYSTEM DEVELOPMENT
1. Outline 4 areas that are considered during the requirement specification stage.
2. Explain at least 3 factors that should be put
STAGES OF SYSTEM DEVELOPMENT
1. Problem recognition and definition
2. Information gathering
3. Requirement specifications
4. System design
5. System coding and testing
6. System implementation
7. System review and mainten
Methods of changing information during system development process
1. State 4 reasons why a firm may decide to computerize its operations.
When the organization wants to improve its quality of internal
processes and service delivery.
Due to technological c
A system -a set of components that interact in a given
environment and within a specified boundary in order to achieve a
goal. E.g. solar system, computer system, human body, bicycle
A subsystem- a system part of larger syst
INFORMATION GATHERING/DATA COLLECTION
System analyst gathers data about the current system and users
needs from both external and internal sources.
Methods of data collection
A. Record inspection
Available documents in connection to the system are referen
Information System Development:
System development process a set of activities, methods, best practices, deliverables, and automated
tools that stakeholders (Chapter 1) use to develop and continuously improve information systems and
It is the coding, installation and testing of the modules and their components i.e. the inputs,
outputs and files. System construction involves:
Coding (Software development)
Testing the new sy
Commercial Application Package Implementation Strategy
Commercial application package a software application that can be purchased and
customized to meet the business requirements of a large number of organizations or a
specific industry. A synonym is co
Computer-Assisted Software Engineering (CAS)
Computer-aided systems engineering (CASE) the use of automated software tools that
support the drawing and analysis of system models and associated specifications. Some CASE
tools also provide prototyping and c
FEATURES THAT DETERMINE THE QUALITY OF A SCREEN.
1. COLOURS-Monochrome display text in me colour i.e B/W
-Colour monitors display text and images in multiple
colours and are expensive.
2. SIZE-Monitor size is expressed in inches, representing the
These are computers that are classified based on the type of data or signal that they process.
Data can either be in Discrete or Analogue form.
Discrete (digital) data-is the one that can be represented as distinct values that do not have
Development of Computers
Pre-Electronic Computer age
During the pre-electronic age, human beings struggled to invent tools that could simplify the day
to day operations. To record and communicate ideas (data and information), pre historic cave
/ a[lo.hi] contains defined Items
/ a |v| = v | < v |
| > v | = v |
v = a[lo]; / could use median-of-3
i = p = lo+1;
j = q = hi;
for (;) cfw_
/ shift i up to next a[i] >= v
unsigned int Word;
Word getBit(BitS b, int i) / get value of i'th bit, 0 or 1
int whichWord = i / 32;
int whichBitPos = i % 32;
Word w = b[whichWord]; / extract one word
#define N 64
int search(int v, int a, int lo, int hi);
int main(int argc, char *argv)
/ command line argument
if (argc < 2) cfw_
fprintf(stderr, "Usage: value\n",argv);
v = atoi