; count number of key presses. the result is in bx register. 
; 
; you must type into the emulator's screen, 
; if it closes, press screen button to re-open it. 

name "keycount"

org  100h

; print welcome message: 
mov dx, offset msg
mov ah, 9
int 21h

xor bx, bx ; zero bx register.    

wait:  mov ah, 0   ; wait for any key.... 
       int 16h

       cmp al, 27  ; if key is 'esc' then exit. 
       je stop

       mov ah, 0eh ; print it. 
       int 10h

       inc bx ; increase bx on every key press. 

       jmp wait


; print result message: 
stop:  mov dx, offset msg2
       mov ah, 9
       int 21h

; print result value in binary: 
mov cx, 16
print: mov ah, 2   ; print function. 
       mov dl, '0'
       test bx, 1000000000000000b  ; test first bit. 
       jz zero
       mov dl, '1'
zero:  int 21h
       shl bx, 1
loop print
; print binary suffix: 
mov dl, 'b'
int 21h


; wait for any key press: 
mov ah, 0
int 16h

ret ; exit to operating system. 

msg db "I'll count all your keypresses. press 'esc' to stop...", 0Dh,0Ah, "$"
msg2 db 0Dh,0Ah, "recorded keypresses: $"