Compilation of learning - Day 19

17.4 Application int 13h interrupt routine disk read and write

3.5-inch floppy: 2 surface, 80 tracks / side, 18 sectors / track, 512 bytes / sector, Size: 1440KB≈1.44MB

Surface number, track number start from 0, 1 sector number from the beginning.

 

The contents of the current screen is saved on disk

the ASSUME CS: code 
code segment 
Start: 
    MOV AX, 0b800h
     MOV ES, AX
     MOV BX, 0 
    
    MOV Al, . 8 ; the number of sectors written 
    MOV CH, 0 ; track number 
    MOV Cl, . 1 ; sector number 
    MOV DL, 0 ; drive No. 
    MOV DH, 0 ; head number (surface) 
    
    MOV AH, 3 ; 2 read, write 3 
    int  13 is 
    
    MOV AX, 4c00h
     int 21H 
code ends 
End Start

 

17 written test including functional subroutines interrupt routine

test program

assume cs:code
code segment
start:
    mov ah,0
    mov dx,36
    mov bx,0b800h
    mov es,bx
    mov bx,160*12+40*2
    
    int 7ch
    
    mov ax,4c00h
    int 21h
code ends
end start

 

Interrupt routine

assume cs:code
code segment
start:
    mov ax,0
    mov es,ax
    mov di,200h
    mov ax,cs
    mov ds,ax
    mov si,offset func
    mov cx,offset funcend-offset func
    cld
    rep movsb
    
    mov bx,0
    mov es,bx
    mov word ptr es:[7ch*4],200h
    mov word ptr es:[7ch*4+2],0
    
    mov ax,4c00h
    int 21h
    
    org 200h
func:
    jmp short main
    table dw func0,func1
main:
    ;cmp ah,0
    ;je func0
    ;cmp ah,1
    ;je func1
    mov al,ah
    mov ah,0
    mov si,ax
    add si,si
    call word ptr table[si]

    mov ax,4c00h
    int 21h
    
func0:
    push bx
    
    ;扇区号
    mov ax,dx
    mov bl,18
    div bl
    inc ah
    mov Cl, AH 
    
    ; track number 
    mov AH, 0 
    mov BL, 80 
    div BL
     mov CH, AH 
    
    ; plane number 
    mov DH, Al 
    
    ; drive letter 
    mov DL, 0 
    
    ; reading 
    mov AH, 2 
    
    ; the number of sectors read 
    mov Al, . 1 
    
    POP BX
     int  13 is 
    
    RET 
    
func1: 
    Push BX 
    
    ; sector number 
    MOV AX, DX
     MOV BL, 18 is 
    div BL
     inc is AH
    mov Cl, AH 
    
    ; track number 
    mov AH, 0 
    mov BL, 80 
    div BL
     mov CH, AH 
    
    ; plane number 
    mov DH, Al 

    ; drive letter 
    mov DL, 0 

    ; write 
    mov AH, . 3 
    
    ; the number of sectors written 
    mov Al, . 1 
    
    POP BX
     int 13H 
    
    RET 

funcend: NOP 
code ends 
End Start

 

Course Design 2