Here's that program, somewhat improved:

'TEMP, by Ralph A. Esquivel, plots degrees F vs time in seconds

SCREEN 9: Xmax = 640: Ymax = 350

FG = 1 'blue foreground

BG = 7 'white background

COLOR FG, BG

CLS

'draw x-axis

X = 40

LINE (X, Ymax - 60)-(Xmax - 10, Ymax - 60)

LOCATE 22, 5

MULT1 = 10

FOR I = MULT1 TO 170 STEP MULT1

PRINT I - MULT1;

IF I = 10 THEN LINE (X + 32, 140)-(X + 32, Ymax - 60)

NEXT I

'draw y-axis

LINE (X, 140)-(X, Ymax - 60)

LOCATE 10

FOR I = 10 TO 0 STEP -1

PRINT I * 10

IF I = 7 THEN LINE (X, Ymax - 60 - 102)-(Xmax - 10, Ymax - 60 - 102)

IF I = 3 THEN LINE (X, Ymax - 60 - 46)-(Xmax - 10, Ymax - 60 - 46)

NEXT I

'plot temperature points

MULT2 = 1.45

READ TIME

FOR I = 1 TO TIME

X0 = I * 3 + 40 - 2

READ T

TEMP = Ymax - 60 - T * MULT2

Y0 = TEMP

CIRCLE (X0, Y0), 2

PAINT (X0, Y0), 1

SLEEP 1 'simulate data at rate of 1 per second

NEXT I

LOCATE 10, 10

PRINT "Press any key to terminate program"

SLEEP

END

'Temperature data:

DATA 14, 32, 42, 49, 55, 60, 64, 67, 69, 70, 69, 70, 71, 70, 71, 0