Convert Character to binary assembly language

Question

Hi i m using dosbox and masm compilor. I want to prompts the user to enter a character, and prints the ASCII code of the character in hex and in binary on the next line. Rep

Answer 1

When you have the value in register, it is stored in CPU in bits (0/1 encoded as low/high current voltage), so it's actually "formatted" in binary!

You just need to output eight characters '0'/'1' per bit, starting from most significant one.

At the moment where you have the character in AL, the code to output the binary form may look like this:

    cx = 8   ; 8 bits to output
bin_loop:
    rcl al,1 ; move most significant bit into CF
    setc bl  ; bl = 0 or 1 by CF (80386 instruction)
    add bl,'0' ; turn that 0/1 into '0'/'1' ASCII char
    call display_bl ; must preserve al and cx
    loop bin_loop

Judging by your usage of cx for loop you are in 16b real mode. So if you also can't use 80386 instructions (setc) (when targetting 8086/80186/80286 CPU, like emu8086 emulator), then this can be achieved in other way (like two instructions for example, instead of one).

From your usage of CF in those loops with shl/rcl I'm sure you will figure something out, it's very similar.