; butterfly  by michael mitchell›; 01/20/85›PROC DEMO2()›CARD A,B,C,D,X,Y,J,K,COL,I,Q›   Graphics(11)››  Poke(710,0)›  Color=00›  A=1 B=1 C=1 D=1›  X=Rand(70)+1›  Y=Rand(190)+1›  J=Rand(50)+1›  K=Rand(190)+1››  For I=1 TO 9400 ›  DO›    Plot(X,Y) ›    Drawto(J,K)›    Plot(J,Y) ›    Drawto(X,K)›    X==+A ›    Y==+B ›    J==+C ›    K==+D ››    Q=Rand(50)›    IF Q>40 THEN  ›      COL==+1  ›    FI  ›    IF COL>14 THEN ›      COL=1 ›    FI››    COLOR=COL››    IF X>=79 THEN A=-A X==+A  FI›    IF J>=79 THEN C=-C J==+C FI›    IF J<=0 THEN C=-C J==+C FI›    IF X<=0 THEN A=-A X==+A FI›    IF Y>=191 THEN B=-B Y==+B  FI›    IF K>=191 THEN D=-D K==+D  FI›    IF K<=0 THEN D=-D K==+D  FI›    IF Y<=0 THEN B=-B Y==+B FI››  OD›RETURN››