ITPEC IP April 2018 Question 21
Topic: Software
The types of programs that are executed at the startup time of a PC are generally classified into three categories: BIOS, OS, and startup services. Which of the following is the list that is arranged in the sequence of the execution of the programs?
Explanation
BIOS → OS → Startup services — each stage is loaded and started by the one before it.
- •BIOS is firmware stored in ROM on the motherboard, so it is the only program that can run at power-on. It checks and initialises the hardware (POST) and loads the boot loader from the boot device.
- •OS: the boot loader loads the operating system kernel into main memory and starts it.
- •Startup services: once the OS is running, it launches the background services and programs registered to start automatically.
Answer (a)
Why not others:
- •(b) — the OS cannot start before the BIOS: it sits on disk and needs the BIOS to initialise the hardware and load it
- •(c) — the BIOS runs first, not last; the OS and its services need the hardware it prepares
- •(d) — startup services are programs managed by the OS, so they cannot run before the BIOS or the OS
Key rule: Booting is a chain: firmware in ROM starts the hardware and loads the OS, and the OS then starts everything that runs on top of it.
Software · AI-written, may contain errors
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