title: Write graphics pixels in 16-bit assembly
body: <p>I'm trying to develop my own very basic operating system for educational purposes. While coding the kernel, I tried to set color to some pixels on screen to make it look better, but I failed.</p>
  
  <p>I used <code>INT 10h</code> with <code>AH = 0CH</code> with video mode <code>13h</code> (320x200 graphics, 256 colors, 1 page) and tried several other modes like <code>01h</code> and <code>03h</code> but they don't work.</p>
  
  <p>This is my complete code:</p>
  
  <pre><code>;set video mode
  mov ah, 00h
  mov al, 13h
  
  int 10h
  
  ;write pixels on screen
  mov ah, 0ch
  mov bh, 0
  mov dx, 5
  mov cx, 5
  mov al, 0100b
  
  int 10h
  </code></pre>
  
  <p>What's wrong with my code?</p>