asm

        org 100h

start:
        mov     ah, $09
        mov     dx, text
        int 21h

        mov     ah, $09
        mov     dx, enter_char
        int 21h

        xor     si, si

        ; input char
        mov     ah, $01
        mov     bl, al
        int 21h

        mov     di, text
        mov     cx, 12

search:
        repne   scasb
        inc     si

        cmp     cx, 0
        jnz     search
        dec     si

        mov     ah, $09
        mov     dx, next_line
        int 21h


        mov     bx, si
        add     bx, '0'
        mov     ah, $02
        mov     dx, bx
        int 21h

        mov     ah, $09
        mov     dx, ans
        int 21h

exit:
        mov     ah, $09
        mov     dx, pak
        int 21h
        mov     ah, $08
        int 21h

        ret

next_line       db 13, 10, "$"
enter_char      db "Enter char to find string:", 13, 10, "$"
pak     db 13, 10, "Press any key to exit...$"
text    db "Hello world$"
ans     db " occurencies$"