Sorry Deb,
This isn't the right forum to discuss it really. We are embedded systems rather than X86, but a BIOS is there to provide a standard place for your operating system to call for very low level functions, like say, refresh the memory, or get me a word from the floppy disk, from the location I specify.

The operating system is the level of code above that. It provides you with (at its highest levels) the DIR command or the RMDIR command, as well as placing a character at position X,Y on the screen or whatever.

A Real Time Operating System does it exactly when you tell it to do, not when the OS thinks it can manage it. Conventional OS like DOS or WIN 95,98 or NT are NOT RTOS systems, the LATENCY, or time from when you ask for something to when it is delivered varies from 0 to infinity !

Only systems like AMX or RTlinux deliver true RTOS operation.

Steve