IMHO BIOS is what starts up your machine the first time around. the BIOS is present in this memery called Flash Memory(type of ROM, but programmable).
the Flash is non-volatile, the battery exisits for volatile pieces of information on the Flash memory die(possibly time and date).
so when you program your flash memory or flash it, you are programmning a new BIOS, so you better know you have programmed the right BIOS or else you are s.......
i dont know how the floppy disk version works, i think when the computer is still on and knows the mobo it has, you can program the PROM from the floppy -> RAM -> flash memory
but if you have messed it up and you turn of the computer, i would think yo uhave had it with programming it yourself, and then you got to take the flash memory to the local tech shop to flash it back in(probably cheaper to get a new flash chip)
correct me if i am wrong or add information to what i have written, woudl appreciate it