linux 0.11下有一個目錄boot,
裏有3個組語檔。
bootsect.s
head.s
setup.s
我們來搞錄一些還沒有feeling的指令
bootsect.s，
260行，

	mov	cx,#256
	sub	si,si
	sub	di,di
	rep
	movw
.....................
load_setup:
	mov	dx,#0x0000		! drive 0, head 0
	mov	cx,#0x0002		! sector 2, track 0
	mov	bx,#0x0200		! address = 512, in INITSEG
	mov	ax,#0x0200+SETUPLEN	! service 2, nr of sectors
	int	0x13			! read it
............................................
	mov	ah,#0x03		! read cursor pos
	xor	bh,bh
	int	0x10
.............................
read_it:
	mov ax,es
	test ax,#0x0fff
die:	jne die			! es must be at 64kB boundary
	xor bx,bx		! bx is starting address within segment
.......................................
	sub ax,sread
	mov cx,ax
	shl cx,#9
....................
	inc track
...................
/*
 * This procedure turns off the floppy drive motor, so
 * that we enter the kernel in a known state, and
 * don't have to worry about it later.
 */
kill_motor:
	push dx
	mov dx,#0x3f2
	mov al,#0
	outb
	pop dx
	ret

movw,xor,outb,ret,inc,shl,test這些指令還沒練習過。
－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
head.s，238行

/*
 *  setup_idt
 *
 *  sets up a idt with 256 entries pointing to
 *  ignore_int, interrupt gates. It then loads
 *  idt. Everything that wants to install itself
 *  in the idt-table may do so themselves. Interrupts
 *  are enabled elsewhere, when we can be relatively
 *  sure everything is ok. This routine will be over-
 *  written by the page tables.
 */
setup_idt:
	lea ignore_int,%edx
	movl $0x00080000,%eax
	movw %dx,%ax		/* selector = 0x0008 = cs */
	movw $0x8E00,%dx	/* interrupt gate - dpl=0, present */

	lea _idt,%edi
	mov $256,%ecx
rp_sidt:
	movl %eax,(%edi)
	movl %edx,4(%edi)
	addl $8,%edi
	dec %ecx
	jne rp_sidt
	lidt idt_descr
	ret

lea,movl,dec,lidt這是一個以設定為主的組語檔

－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
setup.s

一開始一大堆的中斷，

! ok, the read went well so we get current cursor position and save it for ! posterity.

	mov	ax,#INITSEG	! this is done in bootsect already, but...
	mov	ds,ax
	mov	ah,#0x03	! read cursor pos
	xor	bh,bh
	int	0x10		! save it in known place, con_init fetches
	mov	[0],dx		! it from 0x90000.

! Get memory size (extended mem, kB)

	mov	ah,#0x88
	int	0x15
	mov	[2],ax

! Get video-card data:

	mov	ah,#0x0f
	int	0x10
	mov	[4],bx		! bh = display page
	mov	[6],ax		! al = video mode, ah = window width

! check for EGA/VGA and some config parameters

	mov	ah,#0x12
	mov	bl,#0x10
	int	0x10
	mov	[8],ax
	mov	[10],bx
	mov	[12],cx

! Get hd0 data

	mov	ax,#0x0000
	mov	ds,ax
	lds	si,[4*0x41]
	mov	ax,#INITSEG
	mov	es,ax
	mov	di,#0x0080
	mov	cx,#0x10
	rep
	movsb

! Get hd1 data

	mov	ax,#0x0000
	mov	ds,ax
	lds	si,[4*0x46]
	mov	ax,#INITSEG
	mov	es,ax
	mov	di,#0x0090
	mov	cx,#0x10
	rep
	movsb
...................................................
! well, that went ok, I hope. Now we have to reprogram the interrupts :-( ! we put them right after the intel-reserved hardware interrupts, at ! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really ! messed this up with the original PC, and they haven't been able to ! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f, ! which is used for the internal hardware interrupts as well. We just ! have to reprogram the 8259's, and it isn't fun.

	mov	al,#0x11		! initialization sequence
	out	#0x20,al		! send it to 8259A-1
	.word	0x00eb,0x00eb		! jmp $+2, jmp $+2
	out	#0xA0,al		! and to 8259A-2
	.word	0x00eb,0x00eb
	mov	al,#0x20		! start of hardware int's (0x20)
	out	#0x21,al
	.word	0x00eb,0x00eb
	mov	al,#0x28		! start of hardware int's 2 (0x28)
	out	#0xA1,al
	.word	0x00eb,0x00eb
	mov	al,#0x04		! 8259-1 is master
	out	#0x21,al
	.word	0x00eb,0x00eb
	mov	al,#0x02		! 8259-2 is slave
	out	#0xA1,al
	.word	0x00eb,0x00eb
	mov	al,#0x01		! 8086 mode for both
	out	#0x21,al
	.word	0x00eb,0x00eb
	out	#0xA1,al
	.word	0x00eb,0x00eb
	mov	al,#0xFF		! mask off all interrupts for now
	out	#0x21,al
	.word	0x00eb,0x00eb
	out	#0xA1,al

lds si,[4*0x41],out #0xA1,al
目前還不理解的指令，

**小結：**期中來審視一下目標，
要多了解一些組語設定設備的指令，如軟碟機，VGA，所謂中斷的用法。
輸出out比較不理解其意思，在隨後的練習中補強。