为什么我的 BIOS 磁盘读取程序停止而不是打印？

Question

我最近开始了一个编写操作系统的项目，直到“磁盘读取”为止进展顺利。

代码应该加载下一个扇区并打印字母“H”，该字母存储在引导加载程序之外的字节中，位于BIOS默认加载的55AA位签名之外。

org 0x7C00
bits 16

; Variables for CHS conversion
tmp: db 0
sct: db 0
hed: db 0
cyl: db 0
spt: db 0
hct: db 0
bdv: db 0
snm: db 0

mov [bdv], dl

jmp main


; lbaRead
; Reads sectors using LBA
; bx: LBA Address
; ax: Number of sectors
; dl: Drive number
lbaRead:
    ; Read the Disk Geometry
    mov ah, 8
    int 0x13
    inc dh
    mov [hct], dh
    and cl, 0x3F
    mov [spt], cl
    ; Error Handling
    jc err

    ; Convert LBA to CHS
    ; Store Sector to read number (snm)
    mov [snm], ax
    ; Calculate temporary value (tmp) and sector
    mov ax, bx
    mov bx, [spt]
    div bx
    mov [tmp], al
    inc ah
    mov [sct], ah
    ; Calculate Head and Cylinder
    mov ax, [tmp]
    mov bx, [hct]
    div bx
    mov [hed], ah
    mov [cyl], al

    ; Read the disk
    mov ah, 0x02
    mov al, [snm]
    mov ch, [cyl]
    mov cl, [sct]
    mov dh, [hed]
    mov bx, 0x7E00
    int 0x13
    ; Error handling
    jc err
    
main:
    mov bx, 1
    mov ax, 1
    call lbaRead
    mov ah, 0x0E
    mov al, [0x7E00]
    int 0x10
    jmp $

err:
    mov ah, 0x0B
    mov bl, 0x4
    int 0x10
    jmp $

; Pad to 512 bytes and add 0x55AA cap
times 510-($-$$) db 0
db 0x55, 0xaa

代码应该打印一个单独的“H”，它是下一个扇区中的第一个字节。

然而，它并没有打印任何内容，而是停止了。

编辑：到目前为止，我已经做了一些更改，希望能够解决问题。但还没有...

org 0x7C00
bits 16

mov ax, 0
mov es, ax
mov ds, ax

; Variables for CHS conversion
tmp: db 0
sct: db 0
hed: db 0
cyl: db 0
spt: db 0
hct: db 0
bdv: db 0
snm: db 0

mov [bdv], dl

jmp main


; lbaRead
; Reads sectors using LBA
; bx: LBA Address
; ax: Number of sectors
; dl: Drive number
lbaRead:
    ; Read the Disk Geometry
    mov ah, 8
    int 0x13
    ; Error Handling
    jc err
    ; continue
    inc dh
    mov [hct], dh
    and cl, 0x3F
    mov [spt], cl

    ; Convert LBA to CHS
    ; Store Sectors to read number (snm)
    mov [snm], ax
    ; Calculate temporary value (tmp) and sector
    mov ax, bx
    mov bx, [spt]
    div bx
    mov [tmp], al
    inc ah
    mov [sct], ah
    ; Calculate Head and Cylinder
    mov ax, 0
    mov dx, ax
    mov ax, [tmp]
    mov bx, [hct]
    div bx
    mov [hed], ax
    mov [cyl], dx

    ; Read the disk
    mov ah, 0x02
    mov al, [snm]
    mov ch, [cyl]
    mov cl, [sct]
    mov dh, [hed]
    mov bx, 0x7E00
    int 0x13
    ; Error handling
    jc err
    ret
    
main:
    pusha
    mov bx, 1
    mov ax, 1
    mov dl, [bdv]
    call lbaRead
    popa
    
    mov ah, 0x0E
    mov al, [0x7E00]
    int 0x10
    jmp $

err:
    mov ah, 0x0B
    mov bl, 0x4
    int 0x10
    jmp $

; Pad to 512 bytes and add 0x55AA cap
times 510-($-$$) db 0
db 0x55, 0xaa

Answer 1

事实证明整个程序完全是一团糟 值得庆幸的是，命令中的 Micheal Petch 决定重写整个内容

org 0x7C00
bits 16
 
mov ax, 0
mov es, ax
mov ds, ax
mov ss, ax
mov sp, 0x7c00 ; Stack will grow down below the bootloader.
mov [bdv], dl
 
jmp main
 
 
; lbaRead
; Reads sectors using LBA
; bx: LBA Address
; ax: Number of sectors
; dl: Drive number
lbaRead:
    ; Save AX and BX
    mov [snm], ax
    push bx
 
    ; Read the Disk Geometry
    mov ah, 8
    mov di, 0
    int 0x13
    ; Error Handling
    jc err
    ; continue
    ; Int 0x13/ah=8 can set ES to non zero segment
    ; set ES back to 0
    mov ax, 0
    mov es, ax
 
    inc dh
    mov [hct], dh
    and cl, 0x3F
    mov [spt], cl
 
    ; Restore BX clobbered by previous int 13h
    pop bx
 
    ; Convert LBA to CHS
    ; Calculate temporary value (tmp) and sector
    mov dx, 0
    mov ax, bx
    mov bx, [spt]
    div bx
    inc dl
    mov [sct], dl
    ; Calculate Head and Cylinder
    mov dx, 0
    mov bx, [hct]
    div bx
    mov [hed], dl
    mov [cyl], ax
 
    ; Read the disk
    mov ah, 0x02
    mov al, [snm]
    mov ch, [cyl]
    mov cl, [sct]
    mov dh, [hed]
    mov dl, [bdv]
    mov bx, 0x7E00
    int 0x13
    ; Error handling
    jc err
    ret
 
main:
    pusha
    mov bx, 1
    mov ax, 1
    call lbaRead
    popa
 
    mov ah, 0x0E
    mov al, [0x7E00]
    int 0x10
    jmp $
 
err:
    mov ah, 0x0B
    mov bl, 0x4
    int 0x10
    jmp $
 
; Variables for CHS conversion
tmp: dw 0
sct: db 0
hed: db 0
cyl: dw 0
spt: dw 0
hct: dw 0
bdv: db 0
snm: dw 0
 
; Pad to 512 bytes and add 0x55AA cap
times 510-($-$$) db 0
db 0x55, 0xaa