Resource Management (Cambridge (CIE) A Level Computer Science): Revision Note

Resource management

How does an operating system maximise the use of resources?

• The Operating System (OS) is responsible for managing the computer's hardware efficiently to ensure the system runs smoothly

• This is known as resource management and is vital for:

  • Maximising performance

  • Reducing bottlenecks

  • Ensuring multitasking works correctly

Start-up and system loading

• When a computer is switched on, the BIOS (stored in ROM) runs a bootstrap program

• This loads the kernel and essential parts of the OS from the hard disk or flash storage into main memory (RAM)

• On tablets and smartphones, flash memory contains a read-only section for the OS and a second section for apps and user data

• RAM is then used to execute apps and store active data

Kernel

• The kernel is the core of the OS responsible for managing:

CPU resource management – scheduling

• The OS maximises CPU usage through scheduling, which allows multiple processes to be managed efficiently

  • Multitasking ensures that the CPU switches rapidly between processes

  • Different scheduling algorithms (e.g. round-robin, priority-based) are used to share CPU time fairly

Memory resource management

• RAM is allocated dynamically to active programs and system processes

• If RAM is full, the OS may use virtual memory on disk to simulate extra memory

• This allows more programs to run than would otherwise fit in RAM

Input/output management and DMA

• I/O devices are much slower than the CPU, so the OS optimises their use:

  • I/O operations are managed through device drivers and interrupts

  • The Direct Memory Access (DMA) controller allows data transfer between memory and devices without CPU involvement

  • This frees up the CPU to perform other tasks while data is being moved

  • When the transfer is complete, the DMA sends an interrupt to the CPU

Hiding hardware complexity

• The OS provides a user-friendly interface and handles the complexity of interacting with hardware:

  • GUIs make tasks like file transfers easy (e.g. drag-and-drop instead of command-line)

  • Device drivers handle communication with specific hardware

  • Users don’t need to know technical commands, the OS abstracts this complexity

Summary