Which company underwrites old Optiplex BIOS

I could never figure this out

we have seen old Phoenix BIOS in older Dell

and the new ubiquitous Aptio BIOS by American Megatrends

so which company actually wrote the old Optiplex 7010 or the like

BIOS

Is there a tool one can use to reveal the company?

when this is known I can find tools to work with this bios