blob: bf3afb49ee2508ed9bedffab61897ff0a34634a6 (
plain)
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
|
ORG 0x0
BITS 16
_start:
jmp short start
nop
; Setup dummy BIOS Parameter block so a dumb BIOS does not corrupt us
; if it starts messing up with the parameter block
times 33 db 0
start:
; Set CS to 0x07c0 with label step2 as its beginning offset
jmp 0x07c0:step2
step2:
; Setup segments
cli ; Disable interrupts
mov ax, 0x07c0
mov ds, ax
mov es, ax
mov ax, 0x00
mov ss, ax
mov sp, 0x7c00 ; Stack segment starts right before ds
; and grows down to 0x0. This works because
; Intel implements a full descending stack
sti ; Enable interrupts
jmp $
; Message Print routines
print:
mov bx, 0
.loop
lodsb
cmp al, 0
je .done
call print_char
jmp .loop
.done:
ret
print_char:
mov ah, 0x0e
int 0x10
ret
; Fill in to the end and add bootloader signature
times 510 - ($ - $$) db 0
dw 0xAA55
|
