Some computer owners who have only recently begun to master the world of computer technology may not even suspect that in addition to the operating system and various programs that you can use to work with (double-click - installation - launch), there is still a whole area of partially accessible program codes. It is, of course, about the BIOS (BIOS).
Let's see what bios is. To make it more clear, let's start with an example. Imagine an abstract computer on which to load the Windows operating system. We plug the corresponding power cords into sockets and press the power button on the system unit and ... nothing happens, because since we do not know what bios is, then it does not exist on the board. Think about how the computer can “know” that it is necessary to start the download from a particular hard drive, moreover, a particular one? After all, you can boot from a flash drive, a CD, even on a local network. Why winchester? Therefore, we can assume that somewhere in the computer there is a certain software mechanism that allows you to specify where to start the download.
The guess is right! It really is. So we come to the question of what bios is. On any motherboard there is a special microcircuit in which a small control program is entered at the factory. Its functions, of course, are not limited to just choosing a boot device.
The operation of the computer is as follows: all components are supplied with power, their internal controllers perform self-diagnosis tests and, if everything is normal, set the readiness bit. Next, control is transferred to the firmware located in the BIOS chip, it scans the buses for the presence of connected components and polls their status registers. The BIOS then configures the IRQ interrupts and DMA channels for all connected components. Also, in accordance with SPD, delays of the RAM modules and the chipset are set. By the way, CAS can only be configured at this stage while memory is not in use. Now it’s clearer what bios is?
If problems are found, the algorithm is interrupted and an error message is displayed (it may be an inscription on the screen or an encoded squeak of the system speaker).
The user can intervene in the BIOS, making adjustments: the choice of memory delays, the prohibition / activation of many installed components, indicating the polling order of devices to boot the operating system. The changes made are saved due to the standby voltage of the battery located on the board. The basic part of the BIOS remains unchanged. To update it, you need to download a special utility and the corresponding firmware from the motherboard manufacturer's website. With firmware, the old program recorded in the chip is erased, and a new one is written in its place. By the way, to get into the BIOS settings of a personal computer, you must press the Del button immediately after turning on the system unit. After making the desired corrections, do not forget to save them (option in the exit menu). BIOS on a laptop performs the same functions. The only difference is that the settings are much less than a full-fledged computer.
The inscription on the screen that appears when you turn on - Award, Ami or Phoenix Technologies, indicates the types of BIOS. Although there are more of them, these computers are most often used on computers. The principle of work is the same for them. The differences are in the different structure of the menu sections, the number of settings available to the user, and the implementation of the download transfer. Currently, the classic BIOS is gradually giving way to its ideological successor - the UEFI system. In this innovation, many key features of bios were revised. In principle, the name BIOS can be applied to UEFI only with reservations.