Thank you Losethos for the answer.
I was surfing in Google and i have written a little table for fat12, but with no success yet. Here the code.
Code:
[BITS 16] ; We need 16-bit intructions for Real mode
[ORG 0x0]
;TABLA FAT12
jmp start ;3 bytes
oem db "........" ;8 bytes
bytespersector dw 200h ;2 bytes, 512d
sectorspercluster db 1 ;1 bytes
reservedsectors dw 1 ;2 bytes
totalfats db 2 ;1 bytes
maxrootentries dw 224d ;2 bytes, 240d
totalsectorssmall dw 0b40h ;2 bytes, 2880d
mediadescriptor db 0f0h ;1 bytes
sectorsperfat dw 9h ;2 bytes
sectorspertrack dw 12d ;2 bytes
numheads dw 2d ;2 bytes
sectoresOcultos dd 0 ;4 bytes
longitudTotalSect dd 0 ;4 bytes
driverNumber db 0 ;1 bytes
flags db 0 ;1 bytes
signature db 29h ;1 bytes, 41d
id dd 0ffffffffh ;4 bytes
volumelabel db "JMFDOS......" ;12 bytes, 4294967295
systemid db "FAT12..." ;8 bytes
;[ORG 0x7C00] ; The BIOS loads the boot sector into memory fixed location 0x7C00
start:
mov ax,0x7c0
mov ds,ax
;(the rest of the bootstrap...)
With this code i get a non booteable image that after mounted in the floppy can not be readed. When i uncomment "[org 0x7c00]" and erase the 2 lines after the "start" label and quit the diretive "[org 0x0]" in the first line the image works (like in the past).
Sorry for my english.
Is there something wrong with the fat12 table?