Does Xenix use the BIOS for anything?

[Doug Toppin X2075]

This is a question that I believe I know the answer to but would
like to get a confirmation: "Does Xenix use the BIOS in the
[23]86 at all?" My boss has always been convinced that it does
and I believe that it does not.  I am guessing that the Xenix
drivers do everything on their own.  If you know for sure please
post.  The reason that I am interested right now is that I need
to modify some of the characters in the EGA font.  I can find
plenty of DOS examples on how to do this but all of them
reference a BIOS interrupt 0x10.  I believe that to perform the
same function under Xenix I will have to do what the BIOS does
using the termio ioctls for mapping my application to the EGA
card, others believe that all I have to do is write a driver in
assembly that will invoke the associated BIOS function.
We are running SCO Xenix 2.2.3 on the 286.

thanks
Doug Toppin
uunet!melpar!toppin