>I would argue that BIOS is software that is stored in ROM. Quoting from one
>of my textbooks "The BIOS (Basic Input Output System) is the program that
>your computer runs first. It provides the most basic functions of your
>computer, and allows it to load the operating system and perform low level
>tasks like reading the keyboard and displaying information on the screen".
>With a lot of computers you can only upgrade the BIOS by replacing the ROM
>chips. Others (like IBM) are equipped with Flash BIOS which can be upgraded
>by running a special program. According to the instructions for upgrading
>Flash BIOS, if the power is interrupted during the upgrade, the mainboard
>will be rendered useless and will need to be replaced. I suspect it could be
>fixed but would have to go back to the factory and it would cost more than
>getting a new one.
Well, this is only partly true. The greater part of the BIOS usually
resides in the file IO.SYS, a disk file. In addition, you may write
your own device drivers, which exist as separate files. System start
in DOS begins with at address 0FFFF0H, which IS in ROM, this in turn
calls the bootstrap routine which is also in ROM. This in turn calls
the disk bootsrap routine that is NOT in ROM. In turn, this loads
IO.SYS (the BIOS) from disk and, at some stage (perhaps) integrates
those bits of the BIOS that usually ARE in ROM (usually the very
fundamental bits). After that, it gets hairier, invlving things like
SYSINT which usually are on disk, but are linked to some ROM code.
Boiling this down: for DOS systems at least, the proportion of BIOS
that resides in ROM can be 0.0 to 1.0.
Geoff Lambert