10 REM IBM PC
20 REM DEVELOP (Developing economy)
30 CLS
40 SCREEN 1, 0: COLOR 15, 0
50 LINE (0, 0)-(319, 180), 3, B
60 LINE (0, 50)-(319, 50), 3
70 REM coefficients
80 K0 = 2.3
90 K1 = 3
100 K2 = .033
110 K3 = .1
120 K4 = .02
130 K5 = .01
140 K6 = 3
150 K7 = .02
160 K8 = .01
170 K9 = .0067
180 N1 = .0067
190 N2 = .033
200 N3 = .1
210 N4 = .067
220 N5 = .01
230 N6 = .0022
232 N7 = .001
235 N8 = .01
240 REM Sources
250 P1 = 100
260 P2 = 100
270 P3 = 70
280 I0 = 1
290 NE = 3
300 IV = .1
310 IR = .1
320 REM Scaling factors
330 DT = .5
340 T0 = 1
350 N0 = .05
360 A0 = .015
370 M0 = .05
380 D0 = 2
385 F0 = .08
390 REM Starting conditions
400 A = .1
410 N = .3
420 M = .1
430 D = .5
435 F = 10
440 R = I0 / (1 + K0 * N * A + K1)
450 P3 = P3 + 1 * DT
460 DD = IV - N5 * D * M
465 DF = -N8 * F * A
470 DN = K7 * A * N - K8 * N - K9 * N + N1 * A * NE - N2 * R * A * N - N6 * N * N
480 DA = K2 * R * A * N + K3 * R - K4 * A - K5 * A * N + K6 * M / P3 + N7 * F * A
490 DM = P1 * N3 * R + P2 * N4 * R * A * N - K6 * M + IV - N5 * D * M - IR * D
500 A = A + DA * DT
510 IF A < .001 THEN A = .001
520 N = N + DN * DT
530 M = M + DM * DT
540 IF M < .0001 THEN M = .0001
550 D = D + DD * DT
555 F = F + DF * DT
557 IF F < 0 THEN F = 0
560 T = T + DT
570  PSET (T / T0, 180 - N / N0), 1
580  PSET (T / T0, 180 - (A / A0)), 2
590  PSET (T / T0, 50 - M / M0), 2
600  PSET (T / T0, 50 - D / D0), 3
605 PSET (T / T0, 180 - F / F0), 3
610 GOTO 640
620 IF D > 40 THEN IV = 0
630 IF D < 40 THEN IV = .1
640  IF T / T0 < 319 GOTO 440
650  LOCATE 2, 2: PRINT "Develop.bas": SLEEP: SLEEP
660 END