keyboard remapping

alessandro95,

Here's an example I posted some years ago.
I think it provides the basic steps to change any key you like.
Code:
; Modified Keyboard Entry - 13/10/2009 
ORG     256 
mov     ax,cs 
mov     ss,ax 
mov     sp,MyStack+64*2 
mov     ds,ax 
mov     es,ax 
; Some arbitrary modification 
mov     byte [Table+"a"],"z" 
mov     byte [Table+"z"],"a" 
; Save existing Keyboard Interrupt Vector 
push    es 
mov     ax,3509h 
int     21h     ;DOS 'Get Interrupt Vector' 
mov     [Old_09h],bx 
mov     [Old_09h+2],es 
pop     es 
; Setup new Keyboard Interrupt Vector 
mov     dx,New_09h 
mov     ax,2509h 
int     21h     ;DOS 'Set Interrupt Vector' 
; Prompt user action 
mov     dx,Msg1 
mov     ah,09h 
int     21h     ;DOS 'Display String' 
MainLoop:
mov     ah,01h 
int     21h     ;DOS 'Keyboard Input & Echo' 
cmp     al,27   ;<ESC> ? 
jne     MainLoop 
; Restore old Keyboard Interrupt Vector 
push    ds 
lds     dx,[Old_09h] 
mov     ax,2509h 
int     21h     ;DOS 'Set Interrupt Vector' 
pop     ds 
; Terminate 
mov     dx,Msg2 
mov     ah,09h 
int     21h     ;DOS 'Display String' 
mov     ax,4C00h 
int     21h     ;DOS 'Terminate/ReturnCode' 
; ---------------------------------------------- 
New_09h:
push    ax bx si ds 
mov     ax,40h  ;BIOS_DataSegment 
mov     ds,ax 
mov     si,[001Ch]  ;BIOS_KeyboardBufferTailPointer 
; Let BIOS take care of the hardware 
pushf 
call far dword [cs:Old_09h] 
cmp     si,[001Ch]      ;BIOS_KeyboardBufferTailPointer 
je      .t1     ;No new key in buffer 
mov     al,[si] ;ASCII (SCAN in [si+1]) 
mov     bx,Table 
xlat    [cs:bx] 
mov     [si],al ;Updated ASCII 
.t1:
pop     ds si bx ax 
iret 
; ---------------------------------------------- 
ALIGN   4 
Old_09h:
dd      0 
Table:
times 256 db %-1 
MyStack:
dw      64 dup (0) 
Msg1:
db      'Watch <a> and <z> being swapped...',13,10 
db      'Please press some keys. <ESC> exits!',13,10,'$' 
Msg2:
db      "-- That's all folks",13,10,'$' 
; -----------------------------------------------