10 CLS : SCREEN 12
20 CONST var = .1
60 FOR i = 0 TO 39
90 IF i > 21 THEN GOTO 120
100 x = 1: y = 1
110 v = 1: h = 1
120 RANDOMIZE TIMER
125 c = INT(RND * 16)
126 COLOR c
127 NEXT i
150 LINE (x + 1, y + 1)-(v + 1, h + 1), 0, B: LINE (x - 1, y - 1)-(v - 1, h - 1), 0, B
160 x = x + v: y = y + h
170 IF x < 0 OR x > 640 THEN v = -v
180 IF y < 0 OR y > 480 THEN h = -h
'185 IF x = 1 THEN v = -v + var: IF y = 1 THEN h = -h + var
190 LINE (x + v, y + h)-(v, h)
200 FOR i = 1 TO 50: NEXT i
205 A$ = INKEY$
206 IF A$ = CHR$(32) THEN END
207 IF A$ = CHR$(98) THEN CLS
208 'x = x - 1 / 2 * v
210 GOTO 120



