User`s manual

2-7

TROFF

Turns off the Trace function. See

TRON.

TRON

Turns on a Trace function that lets you follow program-flow for debugging

and execution analysis. Each time the program advances to a new program

line, that line number will be displayed inside a pair of brackets.

For example, enter the following program:

10 PRINT "START"

20 PRINT "GOING"

30 GOTO 20

40 PRINT "GONE"

Now type in TRON,

[ENTER]

, and RUN,

[ENTER]

<10> START

<20> GOING

<30> <20> GOING

etc.

(Press SHIFT and @ simultaneously to pause execution and freeze display.

Press any key to continue with execution.) As you can see from the display,

the program is in an infinite loop.

The numbers show you exactly what is going on. (To stop execution, hit

BREAK

key.)

To turn off the Trace function, enter TROFF. TRON and TROFF may be used

inside programs to help you tell when a given line is executed.

For example

TRON

X=X*3.14159

TROFF

might be helpful in pointing out every time line 60 is executed (assuming

execution doesn't jump directly to 60 and bypass 50). Each time these three

lines are executed, <60> <70> will be displayed. Without TRON, you wouldn't

know whether the program was actually executing line 60. After a program is

debugged, TRON and TROFF lines can be removed.