2
這已經有一段時間，因爲我沒有任何ASM，並決定再次嘗試寫一個小的引導程序，用QEMU測試。我的問題是中斷13，出於某種原因進位標誌被設置，所以讀取失敗。目前，我的磁盤映像的樣子：擴展中斷13，閱讀未格式化的磁盤
512字節的BootLoader < - 這（據我所知）是塊0 LBA
主要功能 < - 這將是塊1
基本上，與512個字節的BIOS加載到內存中，我想從相同的驅動器裝載下一個512個字節。但我無法弄清楚發生了什麼問題。希望我已經提供了足夠的信息。
下面的代碼，這個問題是與第二0×13中斷，剛剛跳到0x7E00前：
[bits 16]
[org 0x7C00]
; Prepare Stack Segment
;-----------------------------------------------------------------
mov sp, 0x7A00 ; Move Stack into SP
mov bp, sp ; Store current Stack Base
; Print Character to Make Sure Bootloader Has Reached this Point
;-----------------------------------------------------------------
mov ah, 0x0E ; Print Character to Screen
mov bh, 0x00 ; No Page Numbering
mov bl, 0x07 ; White Text, Black Background
mov al, 65 ; Print Letter A
int 0x10
; Check if INT0x13 Extentions are Supported
;-----------------------------------------------------------------
mov ah, 0x41 ; Set Function 0x41
mov word bx, 0x55AA
push dx ; Save old Drive Identifier
mov dl, 0x80 ; Load 'Active' ID Into dl
int 0x13 ; Call Interupt
jc short unsupported ; If Extentions aren't Supported, Jump
xor ax, ax
add ax, 1 ; Clear Carry Bit
mov si, DAPS ; Load DAPS Struct to DS:SI
mov ah, 0x42 ; Read Functions (AL Ignored)
mov dl, 0x80 ; Active Boot Drive (Commented Out Due to Line 24)
int 0x13
jc short unsupported ; If something goes wrong...
jmp 0x7E00 ; Jump to main
; Errors
;-----------------------------------------------------------------
unsupported:
mov ah, 0x0E ; Print Letter F, Gives Indication of Failure
mov bh, 0x00
mov bl, 0x07
mov al, 70
int 0x10
success:
pop dx ; Pop Original Drive Identifier
jmp $
; Fill Out Rest of Bootloader
;-----------------------------------------------------------------
times 494-($-$$) db 0
; Memory Data Structures and Other Variables
;-----------------------------------------------------------------
; Disk Address Packet Structure (Used For Loading Rest of OS)
DAPS: db 0x10 ; Size of Structure (16 bytes)
db 0 ; Always 0
db 1 ; Number of Sectors to Read (1x512)
db 0 ; Always 0
dw 0x7E00 ; Target Location for Reading To
dw 0 ; Page Table (0, Disabled)
dd 1 ; Read from Second Block
dd 0 ; Large LBAs, ignore
db 0x55, 0xAA ; Add Boot Record Signature
main:
mov ah, 0x0E ; Print Character to Screen
mov bh, 0x00 ; No Page Numbering
mov bl, 0x07 ; White Text, Black Background
mov al, 66 ; Print Letter B
int 0x10
jmp $