Operating system fundamentals

What an operating system does

An operating system (OS) manages hardware and provides services to programs. Its core jobs are:

• Process management — schedule work and share the CPU.
• Memory management — allocate RAM and isolate processes.
• Storage and file systems — organise persistent data.
• Device drivers — talk to hardware.
• Security and access control — decide who can do what.

Types of OS

• General-purpose (Windows, Linux, macOS) — broad hardware, many applications.
• Real-time (RTOS) — guarantees response within a deadline.
• Embedded / IoT — small footprint, low power, often single-purpose.

Why emerging devices need different OSes

An IoT sensor may have 64 KB of RAM and must run for years on a battery. A desktop OS assumes gigabytes of memory and a constant power supply. Emerging OSes therefore strip away features, reduce the kernel, and prioritise predictability.

Check your understanding

• List three core responsibilities of an OS.
• When is a real-time OS required instead of a general-purpose OS?