boot.s

.globl begtext,begdata,begbss,endtext,enddata,endbss
.text
begtext:
.data
begdata:
.bss
begbss:
.text
BOOTSEG = 0x07c0

entry start
start:
        jmpi go,BOOTSEG
go:     mov ax,cs
        mov ds,ax
        mov es,ax
        mov [msg1+17],ah
        mov cx,#20
        mov dx,#0x1004
        mov bx,#0x000c
        mov bp,#msg1
        mov ax,#0x1301
        int 0x10
loop0: jmp loop0
msg1:   .ascii "Loading system ..."
        .byte 13,10
.org 510
        .word 0xAA55
.text
endtext:
.data
enddata:
.bss
endbss: