Program listing of bounce.prg for the Vic 20 
 LOAD address $1001

 0 A=36865:B=36864:D=12:E=32:K=253
 1 C=INT(5*RND(0))
 2 IFC=1THEND=D+1:K=K+1
 3 IFC=2THEND=D-1:K=K-1
 4 IFC=3THENE=E-1:K=K-22
 5 IFC=4THENE=E+1:K=K+22
 6 IFE=60THENE=59
 7 IFD>15THEND=15
 8 IFD<9THEND=9
 9 IFE=0THENE=1
 10 V=INT(7*RND(0))
 11 PRINT"{CLR}":POKE7680+K,102
 12 POKE38400+K,V
 13 IFK<24THENK=253
 14 IFK>483THENK=253
 15 POKEA,E:POKEB,D:GOTO1
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