CSEG segment
assume cs:CSEG, ds:CSEG, es:CSEG, ss:CSEG
org 100h
Start:
	jmp Init
	
	Int_21h_proc proc
		cmp ah,9 
		je Ok_09
		jmp dword ptr cs:[Int_21h_vect]
	Ok_09:
		push ds 
		push dx
		push cs 
		pop ds
		
		mov dx,offset My_string
		pushf 
		call dword ptr cs:[Int_21h_vect]
		pop dx 
		pop ds
		iret 
		Int_21h_vect dd ?
		My_string db 'Моя строка!$'
	Int_21h_proc endp
	
	Init:
		
		mov ah,35h
		mov al,21h
		int 21h
		
		mov word ptr Int_21h_vect, bx
		mov word ptr Int_21h_vect+2, es
		
		mov ax,2521h
		mov dx,offset Int_21h_proc
		int 21h
		
		mov dx,offset Init
		int 27h
CSEG ends
end Start

CSEG segment
assume cs:CSEG, ds:CSEG, es:CSEG, ss:CSEG
org 100h
Start:
	mov ah, 9h
	mov dx, offset t
	int 21h
	
	mov ah, 10h
	int 16h
	
	int 20h
t db 'my text test10.asm!$'
CSEG ends
end Start