	System Files			     Files with the .SYS extension

A file that is an integral part of DOS,   Several files that come with DOS
and must be present on the default disk   have the extension .SYS. An example
for the computer to boot. The two         is ANSI.SYS. These files are not
files are usually hidden files. Their     called "system files". That name is
names are typically IBMBIO.COM and        reserved for the ones described at
IBMDOS.COM, although some versions of     the left.  For information about
DOS may call them IO.COM and MSDOS.COM.   files with the .SYS extension, see
They must be the first two files in 	  the CONFIG.SYS DEVICE topic.
the root directory on the disk, and be 
at the beginning of the disk for the 
computer to boot successfully. FORMAT 
with the /S option and SYS both copy 
them to the proper location.

See the BOOT definition for more information about how these files are used 
during the boot process. 
