[org 0x7c00] [bits 16] pre: cmp ah, 0x0F ; checking if coming from other app or first load - setting ah to 0F before jmping back to the bootloader je welcome mov [bootdev], dl ; Save boot device number jmp welcome welcome: xor ax,ax ; We want a segment of 0 for DS for this question mov ds,ax ; Set AX to appropriate segment value for your situation mov es,ax ; In this case we'll default to ES=DS mov bx,0x1000 ; Stack segment can be any usable memory mov ss,bx ; This places it with the top of the stack @ 0x80000. mov sp,ax ; Set SP=0 so the bottom of stack will be @ 0x8FFFF cld ; Set the direction flag to be positive direction mov ah, 01h ;make cursor invisible mov cx, 2607h int 10h mov ah, 06h ; Set overall background xor al, al ; and clear entire screen xor cx, cx ; Upper left corner CH=row, CL=column = 0 mov dx, 184Fh ; lower right corner DH=row, DL=column = 25 x 80 / textmode mov bh, 1Fh ; YellowOnBlue int 10h mov ah, 06h; top bar, make background xor cx, cx mov dx, 0x004F mov bh, 30h int 10h mov ah, 02h ;top bar setting the position and then write title to it mov bh, 0h mov dh, 0h mov dl, 20h int 10h mov si, title call wolf_print mov ah, 02h ;sets cursor to top to write mov bh, 0h mov dh, 2h mov dl, 1h int 10h mov si, wolf_wel_msg call wolf_print mov si, xpub call wolf_print start: mov ah, 0x00 int 0x16 jmp load_it_all_1 load_it_all_1: mov si, wolf_kernel_load call wolf_print pushf stc mov ah,00 int 13h .read_sector: mov ax, 0x0 mov es, ax ; ES = 0 mov bx, 0x1000 ; BX = 0x1000. ES:BX=0x0:0x1000 ; ES:BX = starting address to read sector(s) into mov ah, 02 ; Int 13h/AH=2 = Read Sectors From Drive mov al, 0x04 ; Sectors to read = 1 mov ch, 00 ; CH=Cylinder. Second sector of disk ; is at Cylinder 0 not 1 mov cl, 02 ; Sector to read = 2 mov dh, 00 ; Head to read = 0 mov dl, [bootdev] int 13h jc wolf_error popf jmp 0x0:0x1000 cli hlt wolf_error: mov si, wolf_error_msg call wolf_print mov si, wolf_error_msg1 call wolf_print mov ah,00 int 16h xor ax,ax int 19h wolf_print: lodsb or al,al jz exit mov ah,0x0e int 10h jmp wolf_print exit: ret over: jmp start ; Moved the data before the boot signature but after the code wolf_wel_msg db 'Welcome to this publication..., press a key to ENTER',0x0D,0x0A,0 wolf_kernel_load db 'Loading program',0x0D,0x0A,0 wolf_error_msg db 'Program not found!',0x0D,0x0A,0 wolf_error_msg1 db 'Press any key to restart..',0 xpub db 0x0D, 0x0A, 0x20, 0xB1, 0x20, 0x20, 0x20, 0xB1, 0x20, 0xB1, 0xB1, 0xB1, 0x20, 0x20, 0xB1, 0x20, 0x20, 0x20, 0xB1,0x20,0xB1,0xB1,0xB1, 0x20, 0x0D, 0x0A,0x20,0x20,0xB1,0x20,0xB1,0x20,0x20,0xB1,0x20,0x20,0xB1, 0x20,0xB1,0x20,0x20,0x20,0xB1,0x20,0xB1,0x20,0x20, 0xB1, 0x0D,0x0A,0x20,0x20,0x20,0xB1, 0x20,0x20,0x20,0xB1,0xB1, 0xB1,0x20,0x20,0xB1,0x20,0x20,0x20,0xB1,0x20,0xB1,0xB1,0xB1,0x20,0x0D,0x0A,0x20,0x20,0xB1,0x20,0xB1, 0x20,0x20,0xB1,0x20,0x20,0x20,0x20,0xB1,0x20,0x20,0x20,0xB1,0x20,0xB1,0x20,0x20,0xB1,0x0D,0x0A,0x20,0xB1, 0x20,0x20,0x20,0xB1,0x20,0xB1,0x20,0x20,0x20,0x20,0x20,0xB1,0xB1,0xB1,0x20,0x20,0xB1,0xB1,0xB1, 0x20, 0 title db 'NOT MY DEFAULT',0 bootdev db 0x80 ; Boot device number times 510-($-$$) db 0 dw 0xAA55