wrboot.asm

这是一本操作系统辅导教材的辅助资料

			;NASM-IDE ASM Assistant Assembler Project File
[BITS 16]		;Set code generation to 16 bit mode
[ORG 0x0100]		;Set code start address to 0100h
[SEGMENT .text]		;Main code segment
mov dx,filename         ;Set Filename
mov ax,3d00h            ;Open For Read
int 21h                 ;Call DOS
jc Error_File           ;Failed to open file
mov dx,buffer           ;set buffer
mov bx,ax               ;set file handle
mov ah,3fh              ;Read File
mov cx,512              ;Read first 512 bytes
int 21h
jc Error_File
mov ah,3eh              ;Close File
int 21h
jc Error_File
rereset:
mov dl,0                ;Disk->A
mov ah,0                ;Reset Disk
int 13h                 ;BIOS Disk
jc rereset
retrydisk:
mov ah,3                ;Ready to Write Disk
mov al,1                ;Number of Sector
mov ch,0                ;clyn=0
mov cl,1                ;sector=1
mov dh,0                ;head=0
mov dl,0                ;drive->A
mov bx,buffer
int 13h
jc retrydisk

End:
mov ax,4c00h            ;Ready to Exit
int 21h
Error_Disk:
mov dx,diskermsg
jmp Display
Error_File:
mov dx,errornofile      ;Failed to openfile
Display:
mov ah,9                ;Ready to Display Message
int 21h
jmp End                 ;Ready to Exit
[SEGMENT .data]		;Initialised data segment
errornofile db "File bootsect.bin not found!",0dh,0ah,"$"
filename db "bootsect.bin",0
successmsg db "Successfully wrote",0dh,0ah,"$"
diskermsg db "Disk Error!",0dh,0ah,"$"
[SEGMENT .bss]		;Uninitialised data segment
buffer resw 512