; fasm example of writing 32-bit program using DPMI 
 
; requires DPMI host installed in system 
 
format MZ 
heap 0					; no additional memory 
 
segment loader use16 
 
	push	cs 
	pop	ds 
 
	mov	ax,1687h 
	int	2Fh 
	or	ax,ax			; DPMI installed? 
	jnz	error 
	test	bl,1			; 32-bit programs supported? 
	jz	error 
	mov	word [mode_switch],di 
	mov	word [mode_switch+2],es 
	mov	bx,si			; allocate memory for DPMI data 
	mov	ah,48h 
	int	21h 
	jc	error 
	mov	es,ax 
	mov	ax,1 
	call	far [mode_switch]	; switch to protected mode 
	jc	error 
 
	mov	cx,1 
	xor	ax,ax 
	int	31h			; allocate descriptor for code 
	mov	si,ax 
	xor	ax,ax 
	int	31h			; allocate descriptor for data 
	mov	di,ax 
	mov	dx,cs 
	lar	cx,dx 
	shr	cx,8 
	or	cx,0C000h 
	mov	bx,si 
	mov	ax,9 
	int	31h			; set code descriptor access rights 
	mov	dx,ds 
	lar	cx,dx 
	shr	cx,8 
	or	cx,0C000h 
	mov	bx,di 
	int	31h			; set data descriptor access rights 
	mov	ecx,main 
	shl	ecx,4 
	mov	dx,cx 
	shr	ecx,16 
	mov	ax,7			; set descriptor base address 
	int	31h 
	mov	bx,si 
	int	31h 
	mov	cx,0FFFFh 
	mov	dx,0FFFFh 
	mov	ax,8			; set segment limit to 4 GB 
	int	31h 
	mov	bx,di 
	int	31h 
 
	mov	ds,di 
	mov	es,di 
	mov	fs,di 
	mov	gs,di 
	push	si 
	push	dword start 
	retfd 
 
 error: mov	ax,4CFFh
	int	21h 
 

  mode_switch dd ?


segment main use32 
 
start:	 mov	  esi, hello
.loop:	 lodsb
	 or	   al,al
	 jz	  .done
	 mov	   dl,al
	 mov	   ah,2
	 int	  0x21
	 jmp	  .loop
.done:

	 mov	  esi, 0x000F0000	  ;; causes page fault with CWSDPMI
	 mov	  eax, [esi]


	 mov	   ax, 0x4C00
	 int	  0x21


hello db 'Hello from protected mode!',0Dh,0Ah,0