BootSector problem

[iocoder]

and the program wich is loaded is this i don't think the ORG directive is correct

Hey, you have already got the answer through your mind

Code: Select all

[ORG 0x0000]

I am making progress i succeded in loading the other program from the sector 2 and load it

Good work man! Go on

[Chandra]

i don't think the ORG directive is correct but what should i put there if it's loaded at 0x1000:0x0000 ?

Seriously, you've no idea how 'Real Mode' addressing works. You really need to read docs on x86 architecture.

And yes, you're right. The ORG directive isn't correct. Now, what you should specify in the ORG directive depends upon how you setup the segment registers. Note that CS:IP must point to 0x10000 because that is the physical address the jump refers to. You can specify ORG 0x10000 and then setup the segment registers to 0 or, you can specify ORG 0 and setup the segment registers to 0x1000. I won't go further than this because you really need to refer to docs that explain about segmentation, memory addressing (real mode and protected mode) and some such.

Cheers.

[opc0de]

Ok i have solved all the problems and succesefully loaded windows mbr at correct address jumped to that adress but now i get an error.It says : couldn't open drive multi(0)disk(0)rdisk(0)partition(1) this error is from NTLDR what the heck is it and how i can bypass it?

[opc0de]

Probably need to call windows mbr exactly in a state it expects from BIOS (e.g. boot drive in DL)

Tried that doesn't work though maybe some other registers need to be initialized

[neon]

If NTLDR is being loaded from the primary boot device successfully by Windows MBR I do not see your boot loader software being the cause. If your software calls the Windows MBR in the same state your MBR was called, your work is done.

[iocoder]

Tried that doesn't work though maybe some other registers need to be initialized

maybe you need to:

Code: Select all

xor bx, bx
mov es, bx
mov ds, bx
mov dl, 0x80
jmp 0x0000:0x7C00

could u try it?

[opc0de]

Nope it doesn't work if you give me your e-mail address i will provide you the source to try to fix it if you have time. Or maybe this error is caused by vmware ? I really don't have a clue...

[Combuster]

if you give me your e-mail address i will provide you the source

Why not attach directly to this thread?

[iocoder]

Nope it doesn't work if you give me your e-mail address i will provide you the source to try to fix it if you have time. Or maybe this error is caused by vmware ? I really don't have a clue...

I think it is better to post your source code here in this thread to allow all of us to help you at all it is up to you! if you want to send me the code you can send it in a message through your User Control Panel here in OSDev, my username is: mostafazizo.
sorry i am afraid i couldn't post my e-mail address because this is not allowed in the forums.

Regards,
Mostafa Abd El-Aziz

[opc0de]

Here is the code :

The boot loader part :

Code: Select all

[BITS 16]

[ORG 0x7C00] 


main:

	cli
	xor bx,bx
	mov es,bx
	mov fs,bx
	mov gs,bx
	mov ds,bx
	mov ss,bx
	mov sp,0x7C00
	sti

	MOV SI, Hello
	CALL PrintString

	MOV AH,0x03
	MOV BH,0x00
	INT 0x10
	ADD DH,2
	XOR DL,DL
	MOV AH,0x02
	XOR BH,BH
	INT 0x10 

	XOR BX,BX
ReadPass:
	MOV AH,0x00
	INT 0x16
	CMP AL,13
	JE Verify
	MOV [read+BX],AL
	PUSH BX
	CALL PrintChar
	POP BX
	INC BX
	CMP BX,6
	JE Verify
	JMP ReadPass
Verify:	
	MOV SI,read
	MOV DI,pass
	MOV CX,6
	REP CMPSB
	JNE the_end

Done:
	MOV SI,succ
	call PrintString
	MOV AH,0x02
	MOV AL,1
	MOV CH,0
	MOV CL,2
	MOV DX,0x0080 	
	MOV BX,1000h
	MOV ES, BX
	XOR BX,BX
	INT 13h
	CMP AH,0
	JNE Done
	jmp   0x1000:0x0000

the_end:
	INT 0x19

PrintChar:
	MOV AH,0x0E
	MOV BH,0x04
	MOV BL,0x10
	INT 0x10
	RET

PrintString:
        MOV AL,[SI]
	CMP AL,0
	JE theret
	INC SI
	CALL PrintChar
	JMP PrintString

theret:
	ret
	pass  db 'MUKMIK',0
	read times 7 db 0
	succ db 'Success booting...',0
	Hello db 'Enter password',0


times 510 - ($ - $$) DB 0
   dw 0xAA55

The part wich loads the original MBR at 7C00h and jumps to it

Code: Select all

[BITS 16]

[ORG 0x0000]

Start:
	
	MOV AH,0x02
	MOV AL,1
	MOV CH,0
	MOV CL,4
	MOV DX,0x0080
	MOV BX,0x0000
	MOV ES,BX
	MOV BX,0x7C00
	INT 13h
	CMP AH,0
	JNE Fail
	cli
	xor bx,bx
	mov es,bx
	mov fs,bx
	mov gs,bx
	mov dl,0x80
	mov ds,bx
	mov ss,bx
	mov sp,0x7C00
	sti
	JMP 0x0000:0x7C00

Fail:
	INT 0x19
	
times 512 - ($ - $$) DB 0

[bluemoon]

I'm not familiar with NTFS but are you sure you not overwriting important data at sector 2, 3, 4, which you used to store your application?

[opc0de]

I thought so at first ... but then i just overwritten sectors 2 and 4 but not the mbr and windows booted up normally... so that's not the problem

[opc0de]

No, usually entire first track is reserved (partitions start on track boundary).

You are way offtopic read something about MBR to refresh your memory...

[Chandra]

No, usually entire first track is reserved (partitions start on track boundary).

You are way offtopic read something about MBR to refresh your memory...

I didn't find anything off-topic.

[opc0de]

No, usually entire first track is reserved (partitions start on track boundary).

You are way offtopic read something about MBR to refresh your memory...

I didn't find anything off-topic.

It has been implemented before and should work if i use the original mbr what it has to do with the first track...anyway maybe i don't get it but if others used the same method and worked it should work for me but it's a mistake in the code.if you find it i owe you a pack of beer.cheers