title: VirtualBox - No bootable medium found
body: <p>There are a lot of question on stackoverflow with the similar title. I read all of them, but none of them answers my problem. This is why I opened this question.</p>
  
  <p>I am creating an operating system in assembler and C. I found that I must compile C code to binary format, extract text section and save it as a file, then convert it to ISO, then mount it to virtual optical dive of diskete and then load my OS in VirtualBox. So, that is a lot of work I want to avoid. I don't want to convert my binary file to ISO every time.</p>
  
  <p>So, I decided to put the binary machine code of my OS to virtual hard drive (<code>VDI</code> file) and then set it to the top of boot order and load it instead of loading from virtual optical drive <code>ISO</code>.</p>
  
  <p>I was researching how <code>VDI</code> works and I found that it is usually dinamically allocated and that only the beginning of data is stored. So, the start of <code>VDI</code> represents a header and the the rest is actual data stored on virtual drive. So, I found that data starts at some address (in my case it is <code>0x00200000</code> from the start of the <code>VDI</code> file).</p>
  
  <p>Then, I basically filled from that address to the end of <code>VDI</code> file with pattern <code>55 AA</code>. So, I suppose it now means that the disk is bootable (because at the end of first sector is still signature <code>55 AA</code>).</p>
  
  <p>I started virtual machine and it says:</p>
  
  <blockquote>
    <p>No bootable medium found! System halted</p>
  </blockquote>
  
  <p>Is there any way to solve this? Why is my virtual disk still not bootable?</p>
  
  <h1>Edit</h1>
  
  <p>Here is actual <code>VDI</code> file: <a href="https://github.com/patakdaca24/test/blob/master/1.vdi?raw=true" rel="nofollow noreferrer">1.vdi</a></p>