bingung assembly,tolong bantu gan..

[Darkc0der]

gan ane dapet coding assembly(contoh program boot sektor) cuma ane ga ngerti.ada yang bsa bantu jelasin??

lagi pengen blajar assembly

ne...

[BITS 16] ; the bios starts out in 16-bit real mode

[ORG 0] ; Data offset = 0

jmp start ; skip over our data and functions, we cannot execute data

; well, you can, but i am not held responsible for the results



; This should be accompanied with an article explaining bootsectors



[BITS 16] ; the bios starts out in 16-bit real mode

[ORG 0] ; Data offset = 0

jmp start ; skip over our data and functions, we cannot execute data :-),



; well, you can, but i am not held responsible for the results

; -------------------------------------

; Data used in the boot-loading process

; ------------------------------------------------------------------------



bootdrv db 0

bootmsg db 'Gareth Owen',39,'s Boot Sector Example',13,10,0

rebootmsg db 'Press any key to reboot',13,10,0



; these are used in the processor identification



processormsg db 'Checking for 386+ processor: ',0

need386 db 'Sorry... 386+ required!',13,10,0

found386 db 'Found!',13,10,0

whatever db 'Insert your code to do something here',13,10,0



;*******************************************

; Functions we are going to use ...

;*******************************************



detect_cpu:

mov si, processormsg ; tell the user what we're doing



call message

; test if 8088/8086 is present (flag bits 12-15 will be set)



pushf ; save the flags original value

xor ah,ah ; ah = 0

push ax ; copy ax into the flags

popf ; with bits 12-15 clear

pushf ; Read flags back into ax

pop ax

and ah,0f0h ; check if bits 12-15 are set

cmp ah,0f0h

je no386 ; no 386 detected (8088/8086 present)

; check for a 286 (bits 12-15 are clear)

mov ah,0f0h ; set bits 12-15

push ax ; copy ax onto the flags

popf

pushf ; copy the flags into ax

pop ax

and ah,0f0h ; check if bits 12-15 are clear

jz no386 ; no 386 detected (80286 present)

popf ; pop the original flags back

mov si, found386



call message

ret ; no 8088/8086 or 286, so ateast 386

no386:

mov si,need386 ; tell the user the problem



call message

jmp reboot ; and reboot when key pressed

; ************************************************** ******************



message: ; Dump ds:si to screen.

lodsb ; load byte at ds:si into al

or al,al ; test if character is 0 (end)

jz done

mov ah,0eh ; put character

mov bx,0007 ; attribute

int 0x10 ; call BIOS

jmp message



done:

ret

; ************************************************** ******************

getkey:

mov ah, 0 ; wait for key

int 016h

ret

; ************************************************** ******************



reboot:

mov si, rebootmsg ; be polite, and say we're rebooting

call message

call getkey ; and even wait for a key



db 0EAh ; machine language to jump to FFFF:0000 (reboot)

dw 0000h

dw 0FFFFh

; no ret required; we're rebooting! (Hey, I just saved a byte

; *******************************************

; The actual code of our boot loading process

; *******************************************



start:

mov ax,0x7c0 ; BIOS puts us at 0:07C00h, so set DS accordinly

mov ds,ax ; Therefore, we don't have to add 07C00h to all our data

mov [bootdrv], dl ; quickly save what drive we booted from

cli ; clear interrupts while we setup a stack

mov ax,0x9000 ; this seems to be the typical place for a stack

mov ss,ax

mov sp,0xffff ; let's use the whole segment. Why not? We can

sti ; put our interrupts back on



; Interestingly enough, apparently the processor will disable

; interupts itself when you directly access the stack segment!

; Atleast it does in protected mode, I'm not sure about real mode.



mov si,bootmsg ; display our startup message

call message

call detect_cpu ; check if we've got a 386



.386 ; use 386 instructions from now on (I don't want to manually include

; operand-size(66h) or address-size(67h) prefixes... it's annoying

mov si,whatever ; tell the user we're not doing anything interesting here

call message

call getkey

call reboot



times 510-($-$$) db 0

dw 0xAA55



tolong bantu jelasin ya agan2....thx b4...