; Tri.asm - sierpinski fractal, assembles to 33 bytes.  Tested using TASM.
; Note - only compatible with MS-DOS, due to startup register state.
; Originally written by James Smith
; Modifications by Daniel Deptford (redmercury@gmail.com)

; If some of the registers look to be initially set in an "undefined" state, that's
; because MS-DOS actually sets them to be in a known state at startup.


.model tiny
CODESEG
STARTUPCODE
        lds si,[bx]
         mov al,13h           ; initialise graphics mode:
         int 10h              ; 320x200x256 at 0xa000
; Do the triangle
         push ds
         pop si
looper: xor al,[si]           ; Initially assumes al=0. Ok?
         mov [si-319],al
         mov al,[si]
         dec si
         jnz looper
         int 16h              ; keystroke? ah is already 0
; Tidy up
         mov ax,3              ; return from graphics mode,
         int 10h              ; back to text
         ret
ENDS
END