Glasswalls

    1 REM                                                          PROGRAM 1.2 (BOUNCING BALL)          (with glass walls)
    2 REM SIMULATES A BALLBOUNCING OFF FLOOR AND WALLS
    3 REM from the book                   Microcomputer Graphics          by  Myers                       converted and                   embellished                     from the apple program          to T/S 2068
    4 REM     by                          James N Jones                   2242 Locust                     Amarillo, Texas 79109             
    5 BORDER 1: PAPER 1: INK 7
    9 LET DX=0: LET V1=1
   10 LET X=50: LET Y=4: LET A=1: LET V=0
   20 CLS : OVER 1
   30 PLOT 0,0: DRAW 0,175: DRAW 255,0: DRAW 0,-175: DRAW -255,0
   40 PLOT X,175-Y: PLOT X+1,175-Y: PLOT X,174-Y: PLOT X+1,174-Y
   50 IF Y>174 THEN GO SUB 5000: IF V=0 THEN LET V=-1
   60 IF X>254-DX THEN GO SUB 6000
   70 IF X<(1-DX) THEN GO SUB 7000
   80 LET V=V+A
   90 PLOT X,175-Y: PLOT X+1,175-Y: PLOT X,174-Y: PLOT X+1,174-Y
  100 LET Y=Y+V: LET X=X+DX
  104 IF V1=0 AND V=0 THEN GO TO 8000
  105 LET V1=V
  110 GO TO 40
 5000 LET V=-V: SOUND 0,22;2,43;4,55;6,31;7,56;9,16;11,2;13,0
 5010 RETURN 
 6000 LET DX=-DX: SOUND 0,33;1,0;7,62;8,16;11,232;12,1;13,0: PAUSE 1
 6010 RETURN 
 7000 LET DX=-DX: SOUND 0,55;2,33;4,77;7,56;8,16;9,16;10,16;11,2;13,0
 7010 RETURN 
 8000 LET DX=ABS DX+1
 8010 GO TO 10
 9998 CLEAR : SAVE "glasswalls" LINE 1