Editing BIOS (section)

=== Setup utility ===
Historically, the BIOS in the IBM PC and XT had no built-in user interface. The BIOS versions in earlier PCs (XT-class) were not software configurable; instead, users set the options via [[DIP switch]]es on the motherboard. Later computers, including most IBM-compatibles with 80286 CPUs, had a battery-backed [[nonvolatile BIOS memory]] (CMOS RAM chip) that held BIOS settings.<ref name="CMOS Battery"/> These settings, such as video-adapter type, memory size, and hard-disk parameters, could only be configured by running a configuration program from a disk, not built into the ROM. A special "reference diskette" was inserted in an [[IBM Personal Computer/AT|IBM AT]] to configure settings such as memory size.<ref>{{cite book | url=https://books.google.com/books?id=56TT-cJeP9wC&dq=bios+cmos&pg=PA358 | title=PC Systems, Installation and Maintenance | isbn=978-1-136-37441-8 | last1=Beales | first1=R. P. | date=11 August 2006 | publisher=Routledge }}</ref>

Early BIOS versions did not have passwords or boot-device selection options. The BIOS was hard-coded to boot from the first floppy drive, or, if that failed, the first hard disk. Access control in early AT-class machines was by a physical keylock switch (which was not hard to defeat if the computer case could be opened). Anyone who could switch on the computer could boot it.{{citation needed|date=March 2013}}

Later, 386-class computers started integrating the BIOS setup utility in the ROM itself, alongside the BIOS code; these computers usually boot into the BIOS setup utility if a certain key or key combination is pressed, otherwise the BIOS POST and boot process are executed.

[[File:Award BIOS setup utility.png|thumb|Award BIOS setup utility on a standard PC]]
A modern BIOS setup utility has a [[text user interface]] (TUI) or [[graphical user interface]] (GUI) accessed by pressing a certain key on the keyboard when the PC starts. Usually, the key is advertised for short time during the early startup, for example "Press DEL to enter Setup". 

The actual key depends on specific hardware. The settings key is most often [[Delete key|Delete]] ([[Acer Inc.|Acer]], [[ASRock]], [[Asus]] PC, [[Elitegroup Computer Systems|ECS]], [[Gigabyte Technology|Gigabyte]], [[Micro-Star International|MSI]], [[ZOTAC|Zotac]]) and [[Function key|F2]] (Asus&nbsp;motherboard, [[Dell]], [[Lenovo]] laptop, [[Origin PC]], [[Samsung]], [[Toshiba]]), but it can also be [[Function key|F1]] (Lenovo&nbsp;desktop) and [[Function key|F10]] ([[Hewlett-Packard|HP]]).<ref>{{cite news |title=How to Enter the BIOS on Any PC: Access Keys by Manufacturer |url=https://www.tomshardware.com/reviews/bios-keys-to-access-your-firmware,5732.html |work=Tom's Hardware |date=4 February 2022 |language=en}}</ref>

Features present in the BIOS setup utility typically include:

* Configuring, enabling and disabling the hardware components
* Setting the [[system time]]
* Setting the boot order
* Setting various passwords, such as a password for securing access to the BIOS user interface and preventing malicious users from booting the system from unauthorized portable storage devices, or a password for booting the system