DEFINT A-Z
DECLARE SUB movepoint ()
COMMON SHARED x, y, c

SCREEN 13: CLS
RANDOMIZE TIMER
DIM Red(63), Green(63), Blue(63)
DIM RedChange(63), GreenChange(63), BlueChange(63)

ChangeRate = 100
start:
x = INT(RND * 320): y = INT(RND * 200)
RedChangeStart = INT(RND * 10) - 5
BlueChangeStart = INT(RND * 10) - 5
GreenChangeStart = INT(RND * 10) - 5

FOR n = 0 TO 63
  RedChange(n) = RedChangeStart
  GreenChange(n) = GreenChangeStart
  BlueChange(n) = BlueChangeStart
    StartRedPalette = n + RedChangeStart
    StartGreenPalette = n + GreenChangeStart
    StartBluePalette = n + BlueChangeStart
  IF StartRedPalette > 63 THEN StartRedPalette = StartRedPalette - 63
  IF StartGreenPalette > 63 THEN StartGreenPalette = StartGreenPalette - 63
  IF StartBluePalette > 63 THEN StartBluePalette = StartBluePalette - 63
    Red(n) = StartRedPalette
    Green(n) = StartGreenPalette
    Blue(n) = StartBluePalette
NEXT

DO
Counter = Counter + 1
IF Counter > ChangeRate THEN Counter = 0
movepoint

IF Counter = 0 THEN
 FOR i = 1 TO 63
  Red(i) = Red(i) + RedChange(i)
  Green(i) = Green(i) + GreenChange(i)
  Blue(i) = Blue(i) + BlueChange(i)
   IF Red(i) > 63 THEN Red(i) = 63: RedChange(i) = -RedChange(i)
   IF Green(i) > 63 THEN Green(i) = 63: GreenChange(i) = -GreenChange(i)
   IF Blue(i) > 63 THEN Blue(i) = 63: BlueChange(i) = -BlueChange(i)
  IF Red(i) < 0 THEN Red(i) = 0: RedChange(i) = -RedChange(i)
  IF Green(i) < 0 THEN Green(i) = 0: GreenChange(i) = -GreenChange(i)
  IF Blue(i) < 0 THEN Blue(i) = 0: BlueChange(i) = -BlueChange(i)
   OUT &H3C8, i
   OUT &H3C9, Red(i)
   OUT &H3C9, Green(i)
   OUT &H3C9, Blue(i)
 NEXT
END IF
k$ = INKEY$
IF UCASE$(k$) = "Q" THEN END
IF k$ <> "" THEN GOTO start
LOOP

SUB movepoint
Direction = INT(RND * 4)
SELECT CASE Direction
 CASE 0
  y = y - 1
  IF y < 0 THEN y = 0
 CASE 1
  x = x - 1
  IF x < 0 THEN x = 0
 CASE 2
  y = y + 1
  IF y > 200 THEN y = 200
 CASE 3
  x = x + 1
  IF x > 320 THEN x = 320
END SELECT
Colour = POINT(x, y) + 1
IF Colour > 63 THEN Colour = 63
DEF SEG = &HA000
POKE y * 320& + x, Colour
DEF SEG
END SUB