Thanks for your reply Kam; On Sun, 2007-08-19 at 10:23 -0800, Kam Leo wrote: > On 8/19/07, Michael Harpe <mharpe79@xxxxxxxxx> wrote: > > The things that happen at power-up on most any modern computer are pretty > > much the same. It's dictated by the need to start in an orderly, known > > fashion every time. The idea of bootstrap programs go all the way back to > > the very early days of computers. > > > > When you push the power button, the system power supply control logic senses > > the closed switch and starts powering up the motherboard. On the motherboard > > there is logic that brings up the chips on the board in the proper sequence. > > > > Once the CPU is powered up properly, the logic on the chip senses that a > > power on reset has occured. The CPU logic is setup in a specific way such > > that the chip starts in a prescribed manner each time. This is the key to > > the whole process. > > > > What happens next varies by according to the individual chip architecture > > but in general this is where the BIOS gets involved. > > > > The BIOS (BIOS means Basic Input Output System) resides in a EEPROM or FLASH > > EPROM on the motherboard. It's been two or three years since I read my stuff on BIOS, so I probably got it wrong or out of date. I will re-read. > This chip contains the program that gets the > > machine started along with the low-level routines that interface the > > operating system with the hardware on the motherboard. The CPU starts by > > loading an address from the last (or first) few bytes of this ROM and > > jumping to that address thus starting the boot process. > > > > What happens next is implementation dependent but basically consists of > > setting the machine up to run an operating system and then loading the boot > > block off of the selected boot device. This is usually the very first sector > > of the hard disk. Once this is completed the same thing happens again, the > > BIOS loads the program into RAM and jumps to it. > > > > Now we're into the loader for the operating system. The loader does more > > preparation for running the OS and loads more of the OS into RAM. The next > > step loads what's called the kernel, which is the core operating system. > > From here you're running the operating system, be it Windows, Linux, > > whatever. > > > > I hope this helps! > > > > Mike Harpe, N4PLE > > Sellersburg, IN > > > > If you want to know more try this site: http://computer.howstuffworks.com/ > How a BIOS works is presented in this article: > http://computer.howstuffworks.com/bios.htm > Kam, I tried to be specific so as not to waste your time with answers I already know. BIOS - I got. (Allowing for a double check). Power on - I don't got. -- Regards Bill
