10 REM IBM
20 REM  SALES: Sales and money
30 CLS
40 SCREEN 1, 0: COLOR 15, 0
50 LINE (0, 0)-(319, 180), 3, B
60 Q = 10
70 J = 1
80 K1 = .005
90 K2 = .005
100 K3 = .05
110 K4 = 1500
120 Q0 = .3
130 P0 = 1
140 M0 = .5
150 T0 = 1
160 DT = 1
170  PSET (T * T0, 180 - Q * Q0), 1
180  PSET (T * T0, 180 - P * P0), 2
190  PSET (T * T0, 180 - M * M0), 3
200 P = K4 / Q
210 DQ = J - K1 * Q - K2 * Q
220 DM = (K2 * Q) * P - K3 * M
230 Q = Q + DQ * DT
240 M = M + DM * DT
250 T = T + DT
260  IF T * T0 < 319 GOTO 170
265 LOCATE 2, 2: PRINT "Sales.bas"
270 SLEEP: SLEEP
280 END