150
IFNDEF model
	model EQU <small>
ENDIF

	DOSSEG
	.MODEL model
	.CODE	

	PUBLIC _vsync

_vsync   PROC

	mov dx,3dah

wt1:	in al,dx
	test al,00001000b
	jnz wt1

wt2:	in al,dx
	test al,00001000b         ;wait until bit is 1
	jz wt2                 ;indicating vertical blank started
	ret

_vsync   ENDP


	END
.

0