string concatenation (dx + "$")

salutations,

we are beginners in assembly and we were trying to make an experimental program. look the code:

Code:

org 100h

;macros
macro print str {push ax
                 push dx
                 mov ah,09h
                 push bx
                 mov bx, str
                 mov dx, bx
                 pop bx
                 int 21h
                 pop ax
                 pop dx}

macro inputh {push ax
             mov ah,01h
             int 21h
             pop ax}
macro input {push ax
             mov dx, 80
             mov ah,0ah
             int 21h
             pop ax}
macro close {mov ax, 4c00h
             int 21h}
jmp start

message db "bem-vindo",10,13,"$"
avizzo db "o que desejas fazer"? $"

start:

print message
print avizzo
input
print 10
print 13
print dx
inputh
close

it's output should be something like this:

bem vindo.
o que desejas fazer? 45 (an input just for example)
45 (the user's input printed)

with the input service 0ah of 21h, the buffer where it will store the user's input would be dx, right?

the (probably) only problem in the code is that the code needs to put the dx together with "$" (concatenation of dx with "$"), because the 21h input server we're using is 09h. but we don't know how the code would look like.

probably something like this? >>

Code:

... mov bx, str + "$" ...

maybe there would be an output service that doesn't require the final "$" to indicate the end of the string?

best regards,

mov ah, 0ah mov dx, buffer int 21h mov ah, 9 mov dx, buffer+2 int 21h buffer db 25 ;24 byte buffer+return db 0 ;any previous input to be remembered=no times 25 db 0 ;heres our buffer filled with 0's db '$' ;for printing out the input