rom as in "read only memory" its not?
i mean back in day maybe but now they are more eprom or eeprom.
on my last asus board you could change the picture during the boot process, mine showed a picture of my pc during the boot process lol
ROM is an acronym for "Read Only Memory". It's actually a very old technology that is no longer used in most computers. It was programmed by the manufacturer based on the specs requested by the buyer and could never be altered.
The next generation was PROM or "Programmable Read Only Memory". It could be programmed by the end user only one time after which it was functionally identical to ROM.
Next was EPROM or "Erasable Programmable Read Only Memory". It could be erased by eposing the silicon die to UV light for a period of time afterwhich it could be reprogrammed. There was a thick layer of clear glass over the die so that the UV light could actually reach the it.
Next was EEPROM or "Electrically Erasable Programmable Read Only Memory". This is the type of ROM that was used to develop flash memory devices and it is the technology on which your BIOS program is stored on your motherboard. Take a look at this article on Wikipedia for more information: http://en.wikipedia.org/wiki/Flash_memory
OK, to answer your question, BIOS is stored on the EEPROM because it is Non-volatile which means that it doesn't go away when the power is turned off. In other words, it is effectively permanent (at least until it is reprogrammed). In addition, EEPROM's can be connected directly to the computers system memory bus and therefore can be assigned to the default startup address of the CPU. That means that the computers startup program, BIOS and default configuration can be stored there so that the CPU can find usable instructions on how to get the computer started after the power is turned on. Here's another Wikipedia article on BIOS: http://en.wikipedia.org/wiki/BIOS