title: Can RAM modification damage hardware?
body: <p>Can a real mode program which can write to arbitrary memory areas, damage hardware? Not included in this scenario are interrupt calls or other things that can be done in real mode -  just pure writing to memory. </p>
  
  <p><a href="http://wiki.osdev.org/Memory_Map_(x86)" rel="nofollow">This page</a> shows a memory map of x86 systems, and I see stuff like BIOS data area; so I fear that writing to this area might do persistent changes to the BIOS, or at least change the BIOS settings to unexpected values. The are probably more things that can be destroyed. </p>
  
  <p>I often read that hardware access in real mode can destroy hardware; but they do not explain the circumstances which have to be made.</p>
  
  <p>Since I am only asking about writing access without invoking interrupts, my main question is, if changes to the memory can do persistent changes; and if yes,  which and why? </p>