.text
	.=0x100

| this routine swaps between the b&w display and the color display
| on the IBM personal computer.  80 character width is always selected

start:	push	ax
	push	ds
	xor	ax,ax		|zero AX
	mov	ds,ax		|use data at very beginning of memory
	xorb	0x410,#0x20	| ?
	movb	al,0x449	| this is the "current video mode"
	cmpb	al,#7		|  if it is 7, the monochrome display
	jz	color		|  is in use, and we swith to color.
mono:	mov	ax,#3		| AH=0 -> set mode, AL=3 -> 80 column color
	int	0x10
	j	exit
color:	mov	ax,#7
	int	0x10
	mov	ax,#0x0501
	int	0x10
wait:	inc	ax
	jnz	wait
	mov	ax,#0x0500
	int	0x10
	mov	ax,#3		|dont ask me why I have to do it twice...
	int	0x10
	
exit:	pop	ds
	pop	ax
	int	0x20
	ret