X0% = 160
Y0% = 100
X1% = 160
Y1% = 100
 
HGR
 
KEY% = 0
COUNTER% = 0
COLOR0% = 1
COLOR1% = 2
DO UNTIL (KEY% = 83 OR KEY% = 115)
  WHILE (COUNTER% < 1000 AND KEY% <> 83 AND KEY% <> 115)
    DX% = SGN ( RND (1) - 0.5) * 1
    DY% = SGN ( RND (1) - 0.5) * 1
    X1% = X0% + DX%
    Y1% = Y0% + DY%
    IF X1% > 320 THEN X1% = 320
    IF X1% < 0 THEN X1% = 0
    IF Y1% > 200 THEN Y1% = 200
    IF Y1% < 0 THEN Y1% = 0
    HCOLOR= COLOR0%
    HPLOT X0%, Y0%
    HCOLOR= COLOR1%
    HPLOT X1%, Y1%
    X0% = X1%
    Y0% = Y1%
    COUNTER% = COUNTER% + 1
    KEY% = PEEK ($00C000)
  WEND
  COUNTER% = 0
  COLOR0% = COLOR0% + 1
  IF COLOR0% = 16 THEN COLOR0% = 1
  COLOR1% = COLOR1% + 1
  IF COLOR1% = 16 THEN COLOR1% = 1
LOOP