1. Executions that produce errors
2. Irregular execution that do not produce errors (mostly logic errors)
Execution that produce errors
Simple programming errors. This is the most common type of program error and is
generally caused by mistakes in program syntax. Such errors result in the following
message being displayed:
SN error P0-10
This message indicates that a syntax error has been detected in line 10 of the
program stored in program area 0. The indicated program line should be chacked
and corrected to allow proper execution.
Program logic errors. This type of error is generally caused by such illegal operations
as division by zero or LOG(0). Such errors result in the following message being
displayed:
MA error P0-10
As before, this message indicates that a mathematical error has been detected in line
10 of the program stored in program area 0. In this case, however, program lines
related to the indicated program line as well as indicated program line itself should be
examined and corrected. When an error message is displayed, the following
operations can be used in BASIC mode to display the line in which the error was
detected.
Shift LIST 10 . .
Shift EDIT 10 . .
Shift LIST . . .
Shift EDIT . . .
The periods contained in LIST . and EDIT . instruct the computer to automatically
display the last program line executed
Irregular execution that do not produce errors
Such errors are also caused by a flaw in the program, and must be corrected by
executing the LIST or EDIT command to examine the program to detect the problem.
The TRON command can also be used to help trace the execution of the program.
Entering T R O N . . puts trace mode ON. Now executing a BASIC program
displays the program area and line number as execution is performed, and halts
execution until . . is pressed. This allows confirmation of each program line, making
it possible to quickly identify problem lines. Executing .T R O F F . . cancels
the trace mode.
5.5 Commands
Though there are a variety of commands available in BASIC for use in programs, the
nine fundamental commands listed below are the most widely used.
The following program reads data items located within the program itself, with a
number of data items being read being determined by input from an operator. The
operator may input any value, but note that values greater than 5 are handled as 5
(because there are only 5 data items in line 180). The program then displays the sum
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