Резидентный обработчик клавиатуры

.model tiny
.code
org 100h
start:
  jmp init
greet db 10,13,'Proizvelas podmena int 09h.',13,10,'$'
bye db 10,13,'Ya vigruzhen!',13,10,'$'
time dw ?
old_9int dd ?
old_1cint dd ?
 
sign dw 0fedch
 
new_1c proc far
  push ax
  push dx
  push di
  push ds
  mov ax,cs
  mov ds,ax
  cmp cs:[time],0
  jne q
 
  mov dx,offset cs:[new_9int]
  mov ax,2509h
  int 21h
 
q: add cs:[time],1
   cmp cs:[time],91
   jne q1
 
  mov dx,word ptr cs:[old_9int]
  mov ax,word ptr cs:[old_9int+2]
  mov di,ds
  mov ds,ax
  mov ax,2509h
  int 21h
  mov ds,di
 
q1: cmp cs:[time],182
    jnz q3
   mov cs:[time],0
 
q3: pop ds
    pop di
    pop dx
    pop ax
    iret
new_1c endp
 
new_9int proc far
  push ax
  push bx
  push di
  push es
  sti
  
;  call cs:[old_9int]
  mov ax,40h
  mov es,ax
 
  in al,60h
  mov di,es:[01Ch]
  mov es:[di],al
  cmp di,03Ch
  je beg
  inc di
  inc di
  jmp save
  beg: mov di,01Eh
  save: mov es:[01Ch],di
 
  in al,61h
  mov ah,al
  or al,80h
  out 61h,al
  mov al,ah
  out 61h,al
 
 
    cli
    mov al,20h
    out 20h,al
    pop es
    pop di
    pop bx
    pop ax
    iret
new_9int endp
 
;-------------------------------------------------------------
 
init: mov time,0
  mov ax,0351ch
  int 21h
  mov ax,es:[bx-2]
  cmp ax,cs:sign
  je outing
  mov word ptr [old_1cint],bx
  mov word ptr [old_1cint+2],es
 
  mov ax,03509h
  int 21h
  mov word ptr [old_9int],bx
  mov word ptr [old_9int+2],es
 
  mov dx,offset new_1c
  mov ax,0251ch
  int 21h
  mov dx,offset Greet
  mov ah,9
  int 21h
 
  mov dx,offset init
  int 27h
 
outing:
  push ds
  cli
 
  mov dx,es:[bx-6]
  mov ax,es:[bx-4]
  mov ds,ax
 
  mov ax,0251ch
  int 21h
 
  mov ds,es:[bx-10]
  mov ax,es:[bx-8]
  mov ds,ax
 
  mov ax,02509h
  int 21h
  pop ds
  sti
 
  push es
  mov ax,es:[2ch]
 
  mov es,ax
  mov ah,49h
  int 21h
 
  pop es
  mov ah,49h
  int 21h
  
  mov dx,offset Bye
  mov ah,9
  int 21h
  mov ax,04c00h
  int 21h
end start