bootloader/boot_sect.asm at master · christinesjx/bootloader · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
; boot sect at address 0x7c00
; in 16 bit real mode

[org 0x7c00]


mov bx, HELLO			; print hello message
call print_string


mov [BOOT], dl

mov bp, 0x8000
mov sp, bp

mov bx, 0x9000
mov dh, 2
mov dl, [BOOT]

call  disk_load

mov dx, [0x9000]
call  print_string


jmp $

%include "disk_load.asm"


HELLO:
	db 'Welcome to my OS', 0

print_string:
    pusha
    mov ah, 0x0e

loop:
    mov al, [bx]
    int 0x10
    add bx, 1
    cmp al, 0
    jne loop
    popa
    ret


; Global  variables
BOOT: db 0

; Bootsector  padding all zero
times  510-($-$$) db 0
dw 0xaa55


;go beyond 512 byte
;see if the second sector is loaded
times  256 dw '!'