auto_save_backup.dat

 .MODEL small
.STACK 256
.DATA 
;Ahmad Hammad 1081443
welcome db 'Ahmad Hammad : 1081443 - project #2',10,13,'$'
line db '-------------------------------------',10,13,'$'
		filename db 'input.txt',0	
		filenameresult db 'output.txt',0	 
	
		handle dw 0   ; will be the file handle. the number that DOS assigns to the open file.
		buffer db 255 DUP ('$')   ; make a plain buffer (not a strange input one like before).  
        
        NLine db 13,10,'$'
		len dw 0  
		len2 db 255   ; we need an input buffer this time.
		
		
	
		act db 0
.CODE 
MOV AX,@DATA 
MOV DS,AX 



mov ah,09h
	lea dx,welcome 
	mov dx, offset welcome 
	int 21h   
	
	  	mov ah,09h
	lea dx,line 
	mov dx, offset line 
	int 21h   


		mov ah,3Dh   ; 3Dh of DOS Services opens a file.
		mov al,0   ; 0 - for reading. 1 - for writing. 2 - both
		mov dx,offset filename  ; make a pointer to the filename
		int 21h   ; call DOS
		mov handle,ax   ; Function 3Dh returns the file handle in AX, here we save it for later use.

	;'DOS Service Function number 3Fh reads from a file.

		mov ah,3Fh
		mov cx,27   ; I will assume ELMO.TXT has atleast 4 bytes in it. CX is how many bytes to read.
		mov dx,offset buffer  ; DOS Functions like DX having pointers for some reason.
		mov bx,handle    ; BX needs the file handle.
		int 21h   ; call DOS

	;Here we will put a $ after 4 bytes in the buffer and print the data read:

		mov dx,offset buffer
		add dx,ax    ; Function 3Fh returns the actual amount of bytes read in AX (should be 4 if
				; nothing went wrong.
		mov bx,dx
		mov byte [bx],'$'   ; byte pointer so we don't mess with the whole word (a word is 16bits).
            
               mov cl,20
               mov bl,1   
               		        	mov dx,offset buffer    ; put the pointer back in DX.
		mov ah,9
		int 21h    ; call DOS Function 9 (Print String).  
                   	mov dx,offset NLine   ; put the pointer back in DX.
		mov ah,9
		int 21h    ; call DOS Function 9 (Print String).    
               
            
                   call to_lower
            return:  
           ; call Print 
            lea si,buffer 
            
   
		        	mov dx,offset buffer    ; put the pointer back in DX.
		mov ah,9
		int 21h    ; call DOS Function 9 (Print String).  
                   	mov dx,offset NLine   ; put the pointer back in DX.
		mov ah,9
		int 21h    ; call DOS Function 9 (Print String).    
;;;;;;;;;;;;;;;;;;;;;;;;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            label:  
            mov al,[si] 
            ;mov dl,al
            ;mov ah,2h
           ; int 21h
            call moving1      
            cmp al,'a'
            jge changeLetter
         ;    cmp al,'A'
        ; jge changeLetter1step
           inc si 
           dec cl
           

          ; mov bl,0 
           jnz label      
;;;;;;;;;;;;;;;;;;;;;;;;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++           
                jz Print
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
           changeLetter: 
           
           cmp bl,1
           je changefirst  
            inc si 
             
           dec cl 
          
           jnz label
           ;;;;;;;;;;;;;;;;  
                jz Print; dont go down     
		         
		          jnz label    
		   changefirst:
		   ;inc si  
		 
		   mov al,[si]
		   sub al,32d  
		   mov [si],al
		   mov bl,0

		    inc si 
          ; dec cl
		   jnz label       
		     ;ret      
		     ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
		   
		     
	         
		  
moving1: 
cmp al,' '
je increment
cmp al,'Z'
jle decrement
 ret
increment:
mov bl,1
ret 

decrement:
mov bl,0
   ret
		  
		
		

   
 to_lower:
lea si,buffer

lower:
mov al,[si]
cmp al,60h
jg inc_di_lo
cmp al,40h
jl inc_di_lo
add al,20h
mov [si],al
inc si
jmp lower
inc_di_lo:
inc si
cmp al,'$'
je return
jmp lower    
  
 
 
 Print:

		mov dx,offset buffer  ; put the pointer back in DX.
		mov ah,9
		int 21h    ; call DOS Function 9 (Print String).   
		
		
		
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
        mov dx,offset filenameresult ; put offset of filename in dx 
mov cx,0 ; clear cx - make ordinary file 
mov ah,3Ch ; function 3Ch - create a file 
int 21h ; call DOS service 
;mov dx,offset  ; put offset of filename in dx 
		mov ah,3Dh   ; 3Dh of DOS Services opens a file.
		mov al,1   ; 0 - for reading. 1 - for writing. 2 - both
		mov dx,offset filenameresult  ; make a pointer to the filename
		int 21h   ; call DOS
		mov handle,ax   ; Function 3Dh returns the file handle in AX, here we save it for later use.

	;Get input:

	;	mov ah,0Ah
		;mov dx,offset buffer
		;int 21h

;	DOS Service Function number 40h writes to a file.

		mov ah,40h
		mov bx,255 ; pointer to number of bytes read from user.
		mov cl,27  ; get the contents of the byte at the pointer.
		; note that even though CX takes the length, CL physically IS the low byte of CX.
		mov dx,offset buffer  ; pointer to the actual data in DX.
		mov bx,handle    ; BX needs the file handle.
		int 21h   ; call DOS
		;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
		mov ah,4Ch
		int 21h      ; Function 4Ch (Exit Program)      
   
		end