title: Figuring out physical address by hand (The IDTR register)
body: <p>I've been trying to figure this one for a long time now and I'm not getting anywhere.</p>
  
  <p>Here is what I'm trying to do:
  At what physical address in protected mode is the interrupt vector number 3 located if the value contained in IDTR is 0x3A000?</p>
  
  <p>I want to find a formula which will help me calculate the physical address of every single byte of the interrupt vector #3's offset and also the physical address of every single byte of the interrupt vector #3's segment.</p>
  
  <p>I've been looking around the internet and there is no solid explanation of how the IDTR to calculate this and I'm really curious.</p>
  
  <p>I'm also curious about how this same physical address is found for the real mode...</p>
  
  <p>If someone can help me find a general formula for solving this kind of a question it would be a blast!</p>