REM Slug by R.G. Weston and pupils
      REM This program evolved rather than being planned!
      DIM X(25),Y(25)
      MODE0
      VDU5
      X(1)=400+RND(200)
      Y(1)=300+RND(200)
      DIR=0
      TAIL=1
      REPEAT
        GCOL0,0
        WASTAIL=TAIL
        TAIL=(TAIL MOD 25)+1
        MOVE X(TAIL),Y(TAIL)
        PRINT;"o"
        CHANGE=RND(1)
        IF CHANGE <.5 THEN DIR=DIR +.1745 ELSE DIR =DIR-.1745
        X=X(WASTAIL)
        Y=Y(WASTAIL)
        NEWX=X+4*COS(DIR)
        NEWY=Y+4*SIN(DIR)
        NEWX=NEWX MOD 1280
        NEWY=NEWY MOD 1024
        IF NEWX <0 THEN NEWX=NEWX+1280
        IF NEWY <0 THEN NEWY=NEWY+1024
        X(TAIL)=NEWX
        Y(TAIL)=NEWY
        GCOL0,1
        MOVE NEWX,NEWY
        PRINT;"O"
      UNTIL INKEY$(10)=" "
      RUN