From MEPIS Documentation Wiki
From Wikipedia: The BIOS (Basic Input/Output System) is boot firmware, designed to be the first code run by a PC when powered on. The initial function of the BIOS is to identify, test, and initialize system devices such as the video display card, hard disk, and floppy disk and other hardware. This is to prepare the machine into a known state, so that software stored on compatible media can be loaded, executed, and given control of the PC.
To check the version of the bios on your machine, open a terminal, become root, and type
dmidecode -s bios-version
More info can be obtained by typing instead
dmidecode | head -n10
Entering the BIOS
When you start to boot or reboot, you need to hit a particular key as soon as your system starts up. Often there is a screen telling you what to hit, but this isn't always the case. If the DEL key doesn't do the trick, try F1, F10, or the ESC key. Sometimes you have to keep hitting it once a second or so until it opens up. Consult your user manual or Google for the correct sequence if nothing else works.
Upgrading the bios
WARNING: be careful when approaching this action. The most common method of upgrading the BIOS is to flash it using an external medium. In order to do this, you need to check what your machine's vendor has made available for your particular model. Then use a search engine to find out the recommended method for your product.