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Overview

The BIOS a Basic Input / Output System is a basic input / output system, whose task is to initialize the hardware during the system boot process and to provide runtime services to the operating systems and programs. The BIOS firmware is preinstalled on the personal computer motherboard and is the first software to start when the computer is turned on. The name comes from the basic input / output system of the CP / M operating system used in 1975. The BIOS, originally patented for the IBM PC, was reverse engineered by companies that began manufacturing compatible systems. The original BIOS also serves as an existing standard.

The BIOS on modern PCs initializes the system's hardware components and loads the boot loader into a mass store MBRwhich then starts the operating system. In the DOS era, the BIOS provided a layer of compatibility for various input and output devices, such as a keyboard, mouse, or monitor, that standardized an interface for applications and the operating system. Newer operating systems do not use the BIOS after boot, but run the various peripherals with direct hardware access.

Most BIOS versions are designed specifically to work with a particular computer motherboard model by managing the devices that make up the motherboard chipset. Originally, the BIOS firmware was stored on the ROM board of the PC motherboard. In modern computer systems, the contents of the BIOS are stored in flash memory so they can be rewritten without having to remove the chip from the motherboard. This allows for easy, end-user updates to the BIOS firmware, which can add new features or fix bugs, but also allows your computer to become infected with BIOS rootkits. In addition, a failed BIOS update can even permanently destroy the motherboard, unless the motherboard has some form of backup of the original BIOS for such cases.

limitations

The BIOS was already present on PCs running MS-DOS in the 1980s. Since then, a lot of time has passed, demands have grown, hardware has evolved, and the BIOS has not evolved with these changes, so it has lagged behind for decades. In the ’80s, a few hundred KB, or 1,44 MB, of a floppy disk was still enough to carry data, but today that capacity isn’t enough to store even a single photo. Hard disks have evolved in the same way, growing from their 10-20 MB size to 6-8 TB today, an increase of about one million times (!) Storage space. The BIOS can only handle the MBR partitioning scheme, which is no longer able to address winchers this size. And there are many other drawbacks that characterize the now obsolete BIOS. The most important of these can now be seen (without claiming completeness) in points here:

• You can only boot from hard disks with an MBR partitioning scheme
• You cannot boot from a partition larger than 2 GB
• The BIOS can only boot in 16-bit processor mode, so it only sees a maximum of 1 MB of memory. This is where the 16 Kbyte memory limits that haunted MS-DOS running on old 286-bit (eg, 386, 640) computers came from.
• You can only initialize one hardware at a time at startup, slowing down the hardware boot process until all hardware is configured.
• The MBR partitioning scheme, which is exclusively supported by the BIOS, only allows a maximum of 4 primary partitions, which is multi-boot systems is a serious obstacle to its construction.
• The MBR is the very first (0) sector of the hard disk, which is 512 bytes in size. This stores the boot loader. This area is very small to store the source code of a more advanced boot loader, so most bootloaders are placed in multiple sections in several sectors of your hard disk (see read here).

Alternative, replacement

So the BIOS has needed to be replaced for a long time. Intel began working on the Extensible Firmware Interface (EFI) specification in 1998. Apple chose EFI when it switched to intel architectures on Macs in 2006, but other PC makers hadn’t followed that back then.

In 2007, Intel, AMD, Microsoft and PC manufacturers agreed on a new one Unified Extensible Firmware Interface (UEFI) specifikációról. This is an industry-standard standard that the Unified Extended Firmware Interface Forum managed by and not just led by Intel. UEFI support for Windows has been introduced with Windows Vista Service Pack 1 and Windows 7. The vast majority of computers available today already use UEFI primarily, but support it in compatibility mode also the BIOS.