The match cannot be perfect,
however.The code used by IBM protected by copyrights which forbid others from legally duplicating it.
instead compatible makers are charged with writing their own BIOS routines without copying IBM's.many companies seek to do that job themselves,others by the necessasry firmware from specialist firms such as amrican mega trends INC,award software or phoenix Technologies LTD.
The distinct parts of the BIOS work separately and distinctly even though the code for earch is contained inside the same silicon chips.it operates like a set of small terminate and stay resident programs (like sidekick or prokey) that are always in memory and at your beck and call.in this case they are always in memory because you can not get them out.such is the nature of nonvolatility. The one function of BIOS that's essential to the compatibility of a computer is its software to hardware link of its resident routiness.
