Computer Studies 7010 O Level 2011 Syllabus Insert

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Computer PioneersComputer Ace Computer Studies O level

Computer Ace Computer Studies O Level

NCC Education Computer Pioneers

This pamphlet incorporates the latest changes in the syllabus and should be used as additional teaching material for the Computer Pioneers Computer Ace course.

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Computer Ace Computer Studies O Level

NCC Education Computer Pioneers

1.

System Analysis and Design (Chapter 6) ........................................................................... 4 1.1. Data Flow Diagrams (New Symbols) ........................................................................ 4 1.2. Action Plans ............................................................................................................ 5 PERT (Project Evaluation and Review Technique) ......................................................... 5 Gantt Charts ........................................................................................................... 6 Critical Path Analysis ............................................................................................... 7 1.3. Testing (Chapter 6 Section 3. Systems Implementation) ......................................... 8

2. 3. 4.

Algorithm Design and Programming Concepts (Chapter 8) .................................................. 9 2.1. For Next loop ....................................................................................................... 9 Video conferencing.........................................................................................................10 Logic Gates and Circuits .................................................................................................12 4.1. Introduction to Logic Gates ...................................................................................... 12 4.2. Truth Tables .......................................................................................................... 13 4.3. Combination of Logic Gates ..................................................................................... 16 4.4. Designing a Simple Logic Network ............................................................................ 19

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NCC Education Computer Pioneers

1. System Analysis and Design (Chapter 6) 1.1. Data Flow Diagrams (New Symbols)

DFD is a pictorial representation that shows the flow of data in a system. It shows the interaction between the entities and system. The symbols used for DFD are:

Process

This symbol is used to represent a process within the system.

This symbol is used to represent an Entity that Entity interacts with the process

Data Store

This symbol is used to represent a data store/file used in the system.

Arrows show the flow of data in the system. Data Flow

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1.2.

Action Plans

PERT (Project Evaluation and Review Technique)PERT is a project management tool that is used to show and analyse the tasks involved in a project. It shows the flow of dependent tasks that must be followed in order to complete the project. PERT charts are used to handle large projects where analysis of task and time allocation is of great importance. They were originally developed in 1950s. The steps used in PERT chart planning are: 1. Identification of activities involved in the project 2. Analysing the sequence of flow of dependencies 3. Developing a network diagram for the above identified activities 4. Estimating the time for each activity identified in Step 1 5. Determining the critical path for the set activities. 6. Updating the PERT chart as the project activities continue Benefits of PERT Ability to identify the expected project completion time Shows the activity start and end dates Helps to identify the probability of completion of tasks before a specified date Shows the critical path activities that directly impact the completion time Shows the activities that have slack time and could lend resources to critical path activities in order to complete the project Activity SymbolDuration of the activity

Earliest Start time of an activity

Earliest finish time of an activity Task name Latest finish time of an activity

Latest Start time of an activity

Slack time

PERT charts are created using series of boxes as shown above. Each box represents an activity or a task.V4.0 August 2011 Page 5 of 22

Computer Ace Computer Studies O Level

NCC Education Computer Pioneers

Example

Duration Earliest Start Earliest Finish

In the above example, there are 2 activities, A and C. Activity A must be completed before Activity C begins. Activity A requires 5 days and Activity C requires 4 days. Therefore this part of the project will require 9 days in total.

Gantt ChartsA Gantt chart is a pictorial representation that illustrates a project schedule. It shows all the tasks and resources needed to complete a project. It is a project management tool that helps to show planned work targets. Example: A Gantt chart for a simple project is given below. The project has 5 tasks. Each task has been allocated the number of days required to complete it.

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In this example, Task 1 (Analyse data) requires 5 days, Task 2 (Design the product) requires 12 days and so on. Task 2 can start after 4 days of work of Task 1 and other activities will follow according to the scheduled start dates. Critical Path Analysis When planning a project, we want to know how long will the project take. When will we be able to start a particular task? If this task is not completed on time, will the entire project be delayed? Which tasks should we speed up in order to finish the project earlier? Critical Path Analysis (CPA) is a pictorial representation for scheduling activities within a project. It helps to determine the time required to complete a project and shows which activities are critical and which are not. The Critical Path is the route through the CPA, which has no idle time in any of the activities. In other words, if there is any delay to any of the activities on the critical path, the whole project will be delayed The total time along this critical path is also the minimum time in which the whole project can be completed.

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Example

In this example, there is a clear sequence of events that have to happen in the right order. If any of the events on the critical path is delayed, then the project cannot be completed on time. Task A-C-F takes 3 + 1 + 3 = 7 weeks Task A-D takes 3 + 2 Task B-E takes 4 + 2 = 5 weeks = 6 weeks

Task A-C-F is said to be the critical path as if it is delayed the entire project would be delayed.

1.3.

Testing (Chapter 6 Section 3. Systems Implementation)

There are three general categories of test data:

Normal data:Valid data in a range that the system is able to handle.

Extreme data:Valid data at the highest or lowest value that can be accepted for a variable.

Abnormal data:Invalid data that should be rejected by the system. Example 1: In the context of numbers within the range of 1 to 200: 1. Normal data: Any number between 1 and 200 2. Extreme data: Both 1 and 200, the maximum and the minimum values 3. Abnormal data: Any number outside the range 1 to 200, any negative number, any alphabetic character or other symbol/character

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Example 2: In the context of an alphabetic value: 1. Normal data: Any letter between a and z 2. Extreme data: Both a and z 3. Abnormal data: Any number or any other symbol/character Example Test CaseField Customer Number Abnormal : -2A Extreme : 9999 System rejects System accepts System rejects System accepts Data type Numeric 4 Normal : 24 Length Test Data Expected Result System accepts System accepts Actual Result

2. Algorithm Design and Programming Concepts (Chapter 8 Section 5. Pseudocodes - Repetition Control Structure)As you have already learned, a repetition control structure has a repetition loop that will end when the condition is false. In addition to the Repeat Until and While Do Endwhile structures, the For Next loop is also a repetition structure.

2.1.

For Next loop

Example 1 Write an algorithm using pseudocode to input 5 numbers and display them. Use a For Next loop. For x = 1 to 5 Input x Print x Next x

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Example 2 Write an algorithm using pseudocode to print 5 * and display them. Use a For Next loop. For x = 1 to 5 Print * Next x Example 3 Write an algorithm using pseudocode to input 25 marks. If mark greater than 50, it should display Pass or otherwise display Fail. Use a For Next Loop. Start Define variable x, mark For x = 1 to 25 Input mark If (mark > 50) then Display Pass Else Display Fail End if Next x

3. Video conferencingVideo conferencing is a communication technology which is also known as video teleconferencing. This allows users to communicate in two or more locations via video and audio transmissions simultaneously (i.e. moving pictures and sound). This