Information and Communication Technology (1+1)

Basic Flowchart symbols

1. Terminal :

The terminal symbol is used to indicate the beginning (start), end (stop), and pauses (halt) in the program logic flow. It is the first symbol and the last symbol in the program logic. In addition, if the program logic calls for a pause in the program, the pause is also indicated with a terminal symbol. A pause is normally used in the program logic under some error conditions.

2. Input/output :

The input/output symbol is used to denote any function of an input/output device in the program. If there is a program instruction to input data from the disk, tape, terminal or any other type of input device, that step will be indicated in the flowchart with an input/output symbol. Similarly, all output instructions, whether it is output on a printer, magnetic tape, magnetic disk, terminal screen, or any output device, are indicated in the flowchart with an input/output symbol.

3. Processing :

A processing symbol is used in the flowchart to represent arithmetic and data movement instructions. Hence, all arithmetic processes of adding, subtracting, multiplying and dividing are shown by a processing symbol. The logical process of moving data from one location of the main memory to another is also denoted by this symbol. When more than one arithmetic and data movement instructions are to be executed consecutively, they are normally placed in the same processing box, and they are assumed to be executed in the order of their appearance.

4. Decision box :

The decision symbol is used in a flowchart to indicate a point at which a decision has to be made, and a branch to one of two or more alternative points if possible. The criteria for making the decision should be indicated clearly within the decision box. Moreover , the condition upon which each of the possible exit paths will be executed should be identified, and all the possible paths should be accounted for. During execution , the appropriate path is followed depending upon the result of the decision.

5. Flow lines :

Flow lines with arrowheads are used to indicate the flow of operation, that is, the exact sequence in which the instructions are to be executed. The normal flow of flowchart is from top to bottom and left to right. Arrowheads are required only when the normal top to bottom flow is not to be followed. However, as a good practice and to avoid ambiguity, flow lines are usually drawn with an arrowhead at the point of entry to a symbol. Good practice also dictates that flow lines should not cross each other, and that such intersections should be avoided whenever possible.

6. Connectors :

 

Whenever a flowchart become complex enough that the number and direction of flow lines is confusing, or it spreads more than one page, it is useful to utilize the connector symbol as a substitute for flow lines. This symbol represents an entry from, or an exit to another part of the flowchart. A connector symbol is represented by a circle, and a letter or digit is placed within the circle to indicate the link. A pair of identically labeled connector symbols is commonly used to indicate a continued flow.

7. Looping : An instruction or group of instructions which changes the program.