2 REM IBM
3 REM DAYPR: DAY SINE PHOTOSYNTHESIS-RESPIRATION
4 CLS
5 SCREEN 1, 0: COLOR 15, 0
6 LINE (0, 0)-(319, 180), 3, B
8 LINE (0, 105)-(319, 105), 3
9  LINE (0, 55)-(319, 55), 3
20 Q = 50
60 Q = 5
80 TN = 1
90 K = .9
100 K1 = .2
110 K2 = .04
120 K3 = .01
130 J = 40 * SIN(T / 15.9)
140 IF J < 0 THEN J = 0
150 JR = J / (1 + K * N)
160 N = TN - K3 * Q
170 DQ = K1 * JR * N - K2 * Q
180 Q = Q + DQ
190 PSET (T, 105 - .5 * Q), 1
200  PSET (T, 180 - 50 * N), 2
210  LINE (T, 55)-(T, (55 - J)), 3
220 T = T + 1
300  IF T < 319 GOTO 130
305 LOCATE 22, 2: PRINT "Daypr.bas"
310 SLEEP: SLEEP
320 END