6 Role of the operating system Flashcards
6.1.5
Explain the role of the operating system in terms of managing memory
Managing memory includes managing what should be kept in RAM for maximum efficiency.
Multitasking systems use slicing to effectively manage all running programs. A slice is the time allocated to each user in a multi-access system or to a program in a multitasking system. The OS uses an interrupt mechanism to suspend a process executed by the ALU and invokes the scheduler to identify the next process to be executed. The interrupt handler is scheduled to allow the OS to switch between processes when their time-slices expire.
The use of virtual memory allows the OS to efficiently manage memory by ensuring that actively used data stays in RAM and less frequently used data is moved to slower storage.
6.1.5
Explain the role of operating systems in terms of managing peripherals
The OS relies on device drivers to handle the communication between hardware, peripherals and the operating system. Every single hardware and peripheral connected to a computer system has a device driver. This piece of software facilitates the communication between the particular piece of hardware and the OS.
6.1.5
Explain the role of operating systems in terms of managing hardware interfaces
The OS abstracts / hides the complexities of the computer’s hardware from the user and software applications. Users and application developers don’t need to know the intricate details of how the hardware works; they interact with a simplified interface provided by the OS.
For example, when typing a document, the word processor application does not bother with the driver of the keyboard
6.1.6 - 6.1.7
Virtual memory and paging
Virtual memory is a memory management technique of the OS where secondary memory can be temporarily used as if it were primary memory (RAM).
Paging is a storage mechanism used to retrieve processes from the secondary storage into the primary memory in the form of pages.
The OS manages virtual memory in units called pages. When the physical RAM is full and a running program needs more memory, the OS decides which data in RAM hasn’t been used recently and moves it to secondary memory to free up RAM. This process is called “paging out”. When the data is needed again, it can be swapped back into RAM in a process called “paging in”.
6.1.6 - 6.1.7
Scheduling
A scheduler organises and manages the execution of tasks or processes that use system resources like the computer’s CPU.
A process scheduler decides the next process to be admitted into the CPU.
6.1.6 - 6.1.7
Policies
The OS has policies that govern how resources such as CPU time, memory, disk space, and I/O devices are allocated to different processes and tasks.
6.1.6 - 6.1.7
Interrupt
An interrupt is a signal sent for the OS to stop the current task and handle a specific event or condition that requires immediate attention.
6.1.6 - 6.1.7
Polling
Polling is the periodic checking of devices by a central device to sample their status. The CPU periodically checks certain registers or sensors to see if some request has been made.
6.1.8
Discuss the advantages of producing a dedicated operating system for a device.
There are two general approaches when developing a dedicated OS for a device:
The first approach is to take an existing OS and adapt it for the particular device. The advantage is that the end user deals with a familiar interface. However, the final product will not be optimised for this particular purpose.
The second approach is to design an OS to fit the particular needs of the device exactly. This approach would lead to an OS optimised for the particular device’s specifications and purpose.
6.1.9
Outline how an operating system hides the complexity of the hardware from users and applications.
The OS presents users and applications with a unified and standardised interface for interacting with the computer system, hiding the intricacies of how the underlying hardware of the computer system operates.
