how do i...

[playmazter76]

how do i activate a bios on a gui mame or know how it worx

[2097]

how do you mean know how it works do ya mean if it works?

[FatTrucker]

Bios files are there for mame to reference when it is trying to emulate an arcade board that requires them.
There shouldn't be any need for an end user to 'run' them, since they don't do anything on their own and are simply a collection of code.
If the bios file is installed in your rom folder and a game that requires it launches then mame automatically searches the rom folder for the related bios file.
So if you are concerned about the bios option in Mame32 just leave it as it is. Mame will do the rest for you.