Radio Shack TRS-80 Model 100 Basic Manual page 110

Experiment #5 Label the Axes
It is usually a good idea to label the scale of your graph. This experiment will show
you how to print both the horizontal and vertical labels. Add the following lines to
your program:
700 FOR X=0 TO 28 STEP 4
710 PRINT@ 284+X, X; NEXT X
720 FOR Y=l TO 7
730 PRINT@ 280-Y*40, 100+Y*50
740 NEXT Y
2000 GOTO 2000
List the program to confirm that it is now:
50 CLS
100 LINE (238,54) - (33,54)
150 LINE -(33,0)
200 FOR X = 33 TO 238 STEP 24
300 PSET (X,53) : NEXT X
500 FOR Y = 51 TO 0 STEP -8
800 PSET (34, Y) : NEXT Y
700 FOR X=0 TO 28 STEP 4
710 PRINT@ Z84+X, X; NEXT X
720 FOR Y=l TO 7
730 PRINT@ 280-Y*40, 100+Y*50
740 NEXT Y
2000 GOTO 2000
Execute the program to confirm that it displays
450
400
350
300
250
200
150
o
4
8
12 16 20 24 28
Note: You will have to press
~
to terminate this program.
Lines
58 -
688 The first part of the program remains unchanged and generates the
axes and the tick marks.
Lines 788 . 718 This FOR/NEXT loop prints the labels along the horizontal axis. The
horizontal (X) axis will be used to represent time in quarters for seven years, so the X
variable ranges from 0 to 28. It is incremented in steps of 4 quarters, so that each year
has a label. The first label (0) is printed under the origin at PRINT@ position 284,
and each subsequent label is printed four columns to the right.
104