Doorway

    1 REM        DOORWAY
    2 REM 
    3 REM Typed from book "Better         Programming For Your            Specyrum and ZX81"
    4 REM By S. Robert Speel
    5 REM Fontana Computer Books
    6 REM 
    7 REM 
   10 INK 1: PAPER 6: BORDER 3: BRIGHT 1: CLS 
   20 PLOT 78,0: DRAW 50,100: DRAW 50,-100
   30 FOR f=100 TO 1 STEP -2: PLOT 128-f/2,100-f: DRAW f,0: NEXT f
   40 FOR f=100 TO 1 STEP -1: PLOT 128-f/2,100+f/2: DRAW f,0: NEXT f
   50 FOR f=0 TO 20: PLOT 128-f,165-f: DRAW f*2,0: NEXT f
   60 FOR f=0 TO 10 STEP 10: PLOT 88-f,20-f*2: DRAW 0,80+f*3: DRAW 80+f*2,0,-PI: DRAW 0,-80-f*3: NEXT f
   70 FOR f=20 TO 100 STEP 2: PLOT 88,f: DRAW INK 0;80,0: NEXT f
   80 FOR f=1 TO 40 STEP 2: PLOT OVER 1;128-f,100: DRAW INK 2; OVER 1;2*f,0,-PI: NEXT f
   90 PLOT 128,100: DRAW 0,-100
   95 PRINT #1;"A demonstration of the graphics possible with the 2068 computer"
  100 FOR f=1 TO 50: FOR g=9 TO 20 STEP 2: INK RND*8: FOR h=0 TO 1: BORDER RND*7: PRINT PAPER RND*8; OVER 1; FLASH 1;AT g+h,11;"          ": NEXT h: NEXT g: NEXT f
 9998 SAVE "doorway" LINE 10