' Langton's ant

CONST W = 100, H = 100
DIM X AS INTEGER, Y AS INTEGER, Dir AS INTEGER
' Set 320x200 graphic video mode
SCREEN 1
' Start in the middle, facing East
X = W \ 2
Y = H \ 2
Dir = 0
DO
  IF POINT(X, Y) <> 0 THEN
    Dir = Dir - 1
    PSET (X, Y), 0
  ELSE
    Dir = Dir + 1
    PSET (X, Y), 3
  END IF
  SELECT CASE (Dir MOD 4)
    CASE 0
      X = X + 1
    CASE 1
      Y = Y + 1
    CASE 2
      X = X - 1
    CASE 3
      Y = Y - 1
  END SELECT
LOOP WHILE X >= 0 AND X < W AND Y >= 0 AND Y < H
END