In personal computer hardware, what does the abbreviation BIOS stand for?

Introduction / Context:
When a computer starts, low level firmware code runs before the operating system loads. On many older and even some modern systems, this firmware is commonly referred to as BIOS. Knowing what BIOS stands for helps you understand its purpose and distinguish it from the operating system and other software. This question checks your ability to recall the full form of a very common computer acronym.

Given Data / Assumptions:

• The acronym in question is BIOS.
• It is related to computer startup and hardware level control.
• Options expand the letters B, I, O and S in various ways.
• Only one expansion matches the standard technical meaning.

Concept / Approach:
BIOS stands for Basic Input Output System. It is firmware stored on a chip on the motherboard and is the first code that runs when you power on the machine. Its job is to initialise and test hardware components, provide low level routines for input and output devices and then pass control to the bootloader of the operating system. The words backup, battery and better used in other options do not describe this role. Therefore, the only correct expansion is Basic Input Output System.

Step-by-Step Solution:

Verification / Alternative check:
Computer hardware manuals, motherboard documentation and basic IT textbooks define BIOS as Basic Input Output System. Many BIOS configuration screens even display this phrase on boot, especially on older machines. Historically, BIOS provided software interrupts that operating systems could call for reading the keyboard, displaying characters on the screen and accessing disks. Newer systems may use UEFI firmware instead, but the term BIOS and its full form remain widely used and documented. None of the alternative expansions offered in the choices appear in credible technical literature.

Why Other Options Are Wrong:

• Backup Input Output System: Suggests a backup or secondary system, which is not the role of BIOS.
• Battery Integrated Operating Setup: Refers incorrectly to a battery and an operating setup; BIOS is not primarily about battery integration.
• Better Integrated Operating System: Describes an operating system, whereas BIOS is separate firmware that runs before the operating system.
• Binary Input Output System: While BIOS routines do work with binary data, this phrase is not the standard or accepted expansion of the acronym.

Common Pitfalls:
A common mistake is to assume that BIOS is itself an operating system because it runs when the computer starts. In reality, it is firmware that prepares the hardware and then loads the operating system from disk. Another error is to choose an option that sounds more modern or advanced, such as better integrated operating system, even though it is incorrect. To avoid confusion, remember that BIOS is simple and low level, so the word Basic in Basic Input Output System accurately reflects its nature.

Final Answer:
BIOS stands for Basic Input Output System.