org 0x7C00
%define SECTOR_AMOUNT 0x10  ;Precompiler defined value for easy changing
jmp short start
nop

                                ; BPB
OEMLabel                db "Example "   ; Disk label
BytesPerSector          dw 512          ; Bytes per sector
SectorsPerCluster       db 1            ; Sectors per cluster
ReservedForBoot         dw 1            ; Reserved sectors for boot record
NumberOfFats            db 2            ; Number of copies of the FAT
RootDirEntries          dw 224          ; Number of entries in root dir
LogicalSectors          dw 2880         ; Number of logical sectors
MediumByte              db 0F0h             ; Medium descriptor byte
SectorsPerFat           dw 9            ; Sectors per FAT
SectorsPerTrack         dw 18           ; Sectors per track (36/cylinder)
Sides                   dw 2                ; Number of sides/heads
HiddenSectors           dd 0            ; Number of hidden sectors
LargeSectors            dd 0            ; Number of LBA sectors
DriveNo                 dw 0                ; Drive No: 0
Signature               db 41               ; Drive signature: 41 for floppy
VolumeID                dd 00000000h    ; Volume ID: any number
VolumeLabel             db "Example    "; Volume Label: any 11 chars
FileSystem              db "FAT12   "   ; File system type: don't change!
start: 
; ------------------------------------------------------------------

                      ;Reset disk system
mov ah, 0
int 0x13              ; 0x13 ah=0 dl = drive number
jc errorpart
                      ;Read from harddrive and write to RAM
mov bx, 0x8000        ; bx = address to write the kernel to
mov al, SECTOR_AMOUNT ; al = amount of sectors to read
mov ch, 0             ; cylinder/track = 0
mov dh, 0             ; head           = 0
mov cl, 2             ; sector         = 2
mov ah, 2             ; ah = 2: read from drive
int 0x13                      ; => ah = status, al = amount read
jc errorpart
jmp 0x8000


errorpart:            ;if stuff went wrong you end here so let's display a message
mov si, errormsg
mov bh, 0x00          ;page 0
mov bl, 0x07          ;text attribute
mov ah, 0x0E          ;tells BIOS to print char
.part:
lodsb
sub al, 0
jz end
int 0x10              ;interrupt
jmp .part
end:
jmp $

errormsg db "Failed to load...",0
times 510-($-$$) db 0
        ;Begin MBR Signature
db 0x55 ;byte 511 = 0x55
db 0xAA ;byte 512 = 0xAA