ASM Community

how do i compile my assembly code into a raw bin file so i can use it in a boot loader?

There was a thread about this already. Do a board search :)

i did, it came up witth junk. i dont know what keywords to search for

what I found is that you have an older version of link that can use 16 bit code. Masm handles that without problems.

Correct me if I'm wrong.

where can i get this 16 bit compiler?

as far as i understand it you compile with masm and use the old link version which you can download at iczelions site: www.win32asm.cjb.net
in the downloads section.

I seem to recall to have read that FASM is able to assemble raw code...

im a loyal masm user. i dont go for non-standard hll-based compilers like fasm/nasm/spasm. but ive got it working. i seem to have to hex edit out 512 bytes of 0s before the code/boot seg wich is also 512 bytes. anyi deas how to get it only the code?

"hll-based compilers like fasm/nasm/spasm" haha. Masm is the most hll of these... anyway, get 16bit linker from iczelions site, then exe2bin from somewhere (it's included in win2k, and it's not hard to write your own).

I'm loyal to what gets the job done the best... especially when it comes to compilers and assemblers...
Lots of good assembly programmers switched from MASM to FASM in the past weeks... loyalty is for relationship and work relations, not for programming imho. ;)
But I see what you mean... :)



FASM, nasm and spasm HLL based? ?_o
Or did you mean that the hll of these assemblers is "non-standard" (then, to what ? MASM?) and afaik the HLL support in these assemblers is provided by macros, unlike MASM where they are built-in.

Regards,

im having trouble with my boot sector, it shows a jumble of letters, but not the message i want it to display

.286

.model tiny, stdcall



      option casemap :none

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

; Simple boot program that prints the letter 'H'

;  and then hangs

; Joel Gompert 2001

;

; Disclaimer: I am not responsible for any results of the use of the contents

;   of this file

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







.code



		; This is where BIOS loads the bootloader





; Execution begins here



entry:

	jmp short begin ; jump over the DOS boot record data





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

; data portion of the "DOS BOOT RECORD"

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

brINT13Flag     DB      90H             ; 0002h - 0EH for INT13 AH=42 READ

brOEM           DB      'MSDOS5.0'      ; 0003h - OEM name & DOS version (8 chars)

brBPS           DW      512             ; 000Bh - Bytes/sector

brSPC           DB      1               ; 000Dh - Sectors/cluster

brResCount      DW      1               ; 000Eh - Reserved (boot) sectors

brFATs          DB      2               ; 0010h - FAT copies

brRootEntries   DW      0E0H		; 0011h - Root directory entries

brSectorCount   DW      2880		; 0013h - Sectors in volume, < 32MB

brMedia         DB      240		; 0015h - Media descriptor

brSPF           DW      9               ; 0016h - Sectors per FAT

brSPH           DW      18              ; 0018h - Sectors per track

brHPC           DW      2		; 001Ah - Number of Heads

brHidden        DD      0               ; 001Ch - Hidden sectors

brSectors       DD      0	        ; 0020h - Total number of sectors

		DB      0               ; 0024h - Physical drive no.

		DB      0               ; 0025h - Reserved (FAT32)

		DB      29H             ; 0026h - Extended boot record sig 

brSerialNum     DD      404418EAH       ; 0027h - Volume serial number (random)

brLabel         DB      'randys disk'   ; 002Bh - Volume label  (11 chars)

brFSID          DB      'FAT12   '      ; 0036h - File System ID (8 chars)

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





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

;  Boot program code begins here

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

; boot code begins at 0x003E







nop

nop

nop

nop

nop

nop

nop

begin:

	xor	ax, ax		; zero out ax

	mov	ds, ax		; set data segment to base of RAM

    mov ss,ax

    mov	sp, 7D00h

	mov	bp, sp

	mov	si, offset msg		; load address of our message

	jmp	putstr		; print the message



hang:

	jmp	hang		; just loop forever.





putstr:

	;lodsb		; AL = [DS:SI]

    mov al, byte ptr DS:[SI]

	or al, al	; Set zero flag if al=0

	je hang	; jump to putstrd if zero flag is set

	mov ah, 0Eh	; video function 0Eh (print char)

	mov bx, 0007h	; color

	int 10h

    inc si

	jmp putstr



    

 msg	db	'Randys Operating system',0



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

d:



	times	db (512 - (offset d - offset entry) - 2)  dup(0)



	db	55h, 0AAh		;2  byte boot signature

    end entry

i had to add 7c00 to the offset!!!!!i dont know the tiny memory model, how do i get the complete memory address?

I anm glad there are still a few MASM purists who enjoy the sheer low level grunt of MASM.

Regards,

hutch@movsd.com

Qages,

the boot sector is not read to the base of ram. It is read to 7C00h. You have to set DS accordingly, or add the 7C00h manually as you have done.

You can look here for more info: http://www.nondot.org/sabre/os/articles/TheBootProcess/
specifically: http://www.nondot.org/sabre/os/files/Booting/BootSector.html

--Chorus

Yep, better set up your segments manually, and don't reference anything through CS... some BIOSes are broken in the way they set up CS:IP (ie, some have 0:7C00, some have 7C0:0).

This is the start of a working boot sector code:

		.386





@pushws	macro value

		db 6ah

		db value

		endm



@pushdws	macro value

		db 66h

		db 6ah

		db value

		endm



_TEXT	segment use16 'CODE'



		assume ds:_TEXT



		org 7C00h



L0100:

		jmp L015A

		nop

L7C03	db "MSWIN4.1"

L7C0B:

		db 11h dup(0)

L7C1C	dd 0

		db 27h dup(0)

		db 11 dup(0)		;label

		db 8 dup(0)			;"FAT32   "



L015A:

		cli

		xor   cx,cx

		mov   ss,cx

		mov   sp,7BF8h

		mov   es,cx

		mov   bp,0078h

As f0dder tells, better dont use simplified segment directives.

Also, you might want to use nasm for bootsector writing... direct binary output and better opcode controls are advantagous when dealing with code like this.

You can get the nice bootsector example here: http://fasm.sf.net/phboot.zip (I'm sorry, it's written for fasm ;))

used nasm for it, fasm is stupid!

This opinion is stupid, too.
What is stupid about FASM in your opinion?