Hi there,

I'm trying to build a bootsector. I want the bootsector to print some letter on the screen. For that I'm using GAS assembly and writen the following code:

.global _start
_start:
mov 0xb800, %ax
mov %ax, %es
movb $0x41, %es:0
movb $0x1f, %es:1

loop1: jmp loop1


For some reason this doesn't work. I'm trying to run it using Bochs and using rebooting of my machine, both give the same result - Nada !

Can someone please help me and show me some code that really works ? That will be great !

Thanks,
doron

are you sure you want to jump to the same line over and over again?
___________

this *may* be a reason why:

your moving 2 bytes to register ax (how big is a register). try a move word?

~schneidz

Hi All
After almost two weeks, I've found the solution.
The problem was that I had to include .code16 directive at the top of the code so the compiler will compile it in a 16bit mode

Here is the final code plus the compiler and linker commands I've used

file: bootsect.s:

.code16

.global _start
_start:
xor %ax, %ax
mov $0xb800, %ax
movw %ax, %es
movb $0x41, %es:0
movb $0x1f, %es:1

loop1: jmp loop1



as -o bootsect.o bootsect.s
ld -Ttext 0x7C00 -Tdata 0x7C00 --oformat binary bootsect.o -o bootsect.binary

Yes folks thats it, thats what took me about two weeks !!!!