This preview shows page 1. Sign up to view the full content.
Unformatted text preview: . 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, that also is indicated with a terminal symbol. A pause is normally
used in the program logic under some error conditions or if forms had to be changed in
the computer's line printer during the processing of that program.
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 a
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 a flowchart to represent arithmetic and data
movement instructions. Thus, 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. 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 is possible.
Figure 11.2 shows three different ways in which a decision symbol can be used. It may be noted from these examples that the criterion 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 arrow heads ar...
View Full Document
This document was uploaded on 04/07/2014.
- Spring '14