10 X1=7
20 Y1=8
30 X2=12
40 Y2=9
50 X1D=1
60 Y1D=1
70 X2D=-1
80 Y2D=-1
90 R=RND AND 2 +1
95 X1=X1+X1D:Y1=Y1+Y1D
96 X2=X2+X2D:Y2=Y2+Y2D
100 IF X1<0 THEN X1D=R
110 IF X1>31 THEN X1D=-R
120 IF Y1<0 THEN Y1D=R
130 IF Y1>15 THEN Y1D=-R
140 IF X2<0 THEN X2D=R
150 IF X2>31 THEN X2D=-R
160 IF Y2<0 THEN Y2D=R
170 IF Y2>15 THEN Y2D=-R
175 CLS
180 LINE X1,Y1,X2,Y2,1
190 GOTO 90
