Pressing the f2 key during bootup accesses the cmos setup utility stored in the bios. This is usually stored in a flash rom however historically was either stored in eprom or true rom chips. the cmos only stors the configuration settings as it is low power hardware and used to cost a lot of money. In old computers there was only 128 or 256 bytes of cmos, in newer machines there is as much as 4k ACPI NVS 9non-volatile storage) along with escd (extended system configuration data) and the bios configuration information. Historically the cmos configuration information was stored in memory on the realtime chip, often a Dalace semiconducters part although there were clones. The original question was will erasing partitions delete the bios. The answer to this is no, the bios is stored on a flash chip, and is responsible for booting a computer including the power on self test, changing and interpreting cmos settings, and basic input and output services. these include keyboard (int 09 and 16h) screen, int 10h, disk services, int 13h, printer services, int 14h, bootstrap functions, int19h and memory allocation services and other misc functions int 15H. Modern pcs still use the bios to bootstrap the machine; after all grub uses extended int 13h functions to load sectors from the hard or floppy disks, and in the case of the eeepc the sd and usb subsystems can show as bios drives. in fact hitting escape at boot instructs the bios which has control at this point to show a boot menu showing which drive should be treated as bios drive 0x80 or the first bios hard disk. hitting f2 at boot accesses the setup utility. I think this utility is often copied into ram from the flash chips in order to cause it to run faster, or it is shadowed. I have spent many an hour in my younger days disassembling parts of bios to see how they worked, along with various timer tick routines that certain access software used. There are many stories of dos based /b /bios -b /cga and other switches; telix would write communications input and output through bios to the screen if you told it to do cga snow-checking. this made the screen talk with various screen readers and allowed the screen readers to track the menu bars using their own methods. Regards, Kerry. ----- Original Message ----- From: "Jude DaShiell" <jdashiel@xxxxxxxxxxxxxx> To: <speakup at braille.uwo.ca> Sent: Monday, February 04, 2008 4:41 AM Subject: re: well I got one too > Nobody has ever accessed a bios by pressing f2 on booting up any computer > ever manufactured. What they did access and do access is the CMOS. > Completely different thing, and anyone who has spent a considerable number > of years using versions of DOS separate from windows and screen readers > with speech synthesizers can prove that. Bios writes have to do with > screen output and differ from faster screen writes. The difference with > the older screen readers is that those were able to handle bios writes > fine but the faster screen writes either couldn't be handled or could be > handled with difficulty. Every agt game ever made had a run program with > it and when you played the game with something like run tark /bios then > the screen reader could speak. Also int10 writing in assembly language is > bios screen writing. The Cmos is a memory chip that holds a computer's > time and date and information about hard drive and other peripherals. > > > > _______________________________________________ > Speakup mailing list > Speakup at braille.uwo.ca > http://speech.braille.uwo.ca/mailman/listinfo/speakup >
