ITPEC IP April 2025 Question 18
The types of programs that are running when a PC is started are broadly classified into three (3) categories, namely BIOS (Basic Input Output System), OS, and resident application programs. Which of the following is the order of execution of the programs?
Explanation
BIOS, OS, resident application programs — 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 and loads the OS from the boot device.
- •OS: its kernel is loaded into main memory and started; it then provides the services programs need.
- •Resident application programs: once the OS is running, it launches the programs registered to start automatically and stay in memory, such as antivirus software.
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 the applications need the hardware it prepares
- •(d) — resident applications 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.
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