1.2.1 Systems Software Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What features are provided by an operating system?

A

Provides a user interface

Manages hardware (peripherals)

Manages CPU usage / Interrupts

Provides utilities

Manages Memory

Provide system security (user permssions)

Provides a platform for software to run

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the key facts about memory management?

A

Provides security as it does not let programs access memory reserved for other programs.

Ensures that RAM is used efficiently and not wasted.

Removes data not needed anymore (garbage collection) and allocates memory to applications.

Provides multitasking as it allows multiple programs to run at once

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the key facts about paging

A

Physical addressing with fixed-size divisions –

Data can be held non-contiguously and makes the best use of storage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the key facts about segmentation?

A

Logical addressing with variable size divisions.

This can leave gaps in RAM due to differing sizes of segments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the key facts about virtual memory?

A

Uses secondary storage (HDD)

Pages not currently needed get moved to virtual memory to create room

Pages are swapped between virtual memory and RAM as nothing can be running from virtual memory.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an interrupt?

A

A signal to the processor indicating a device/process needs attention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens when an interrupt is received?

A

If it is of a higher priority, the CPU finishes its current FDE cycle.

The contents of the CPU’s registers are copied to a stack in memory.

The location of the appropriate interrupt service routine is loaded into the program counter.

When complete, the previous contents are popped from the stack and loaded back into the registers.

If the interrupt is of a lower/equal priority to the current process, then the current process continues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are virtual machines?

A

A theoretical computer that runs like software

Shares the resources with the actual OS that it is running on

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the benefits of virtual machines?

A

Allows you to run the software on several different systems without needing multiple physical machines.

Protects the physical machine from a virus as the VM can quickly be reset to its original state.

Some VM are used to execute intermediate code (Java)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the purpose of scheduling (CPU Management)

A

Used to process as many jobs as possible in the least possible time

Ensures all jobs are processed fairly

Enables the most efficient use of the processor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the five main types of scheduling algorithms?

A

Round Robin (RR)

First come first served (FCFS)

Shortest job first (SJF)

Shortest remaining time (SRT)

Multi-level feedback queues (MLFQ)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe round-robin scheduling

A

Each process is given a fixed equal time slice

If the process is not completed, then it joins the back of the queue and the next one starts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe first come first served scheduling.

A

Jobs are processed to completion in the order in which they arrive (First in First Out)

The job will be completed before the next one starts

Each job has an equal priority.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the shortest job first scheduler.

A

Picks the job that will take the shortest time and runs it until it finishes

Needs to know the time each job will take in advance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the shortest remaining time scheduler.

A

The quickest job is completed first but stops and re-evaluates when a new job arrives.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe multi-level feedback queues

A

Uses several queues

Each queue has a different priority

The algorithm can move jobs between these queues

17
Q

What are the 5 main types of operating systems?

A

Distributed

Multi-User

Real-time

Multi-Tasking

Embedded

18
Q

Describe a distributed OS

A

Shares processing between the processors on a network

Allow multiple computers to be treated as one

Multiple computers work on the same problem, completing it quicker

Example: Video Rendering / SETI

19
Q

Describe a multi-user OS

A

Allows multiple users to use the same computer at the same time

Each user is given a time slice of the processor

Example: Mainframe

20
Q

Describe a real-time OS

A

Offers a guaranteed response time

Will make decisions and act immediately

Example: Self-Driving Cars & Airplane Auto Pilot

21
Q

Describe an embedded OS

A

Has limited function and is read-only – stored in ROM.

System software used to manage the device

Built into the device itself

Specific to the hardware/purpose

Examples: Washing machines & Microwaves

22
Q

Describe a multi-tasking OS

A

Allows the user to run more than one program at the same time.

Example uses include running word processing software whilst checking emails.

Example: Typical home/personal computer OS

23
Q

Describe and give examples of a device driver

A

A program that enables communication between an operating system and a hardware device.

Example: Printer drivers| Graphics Card drivers| Sound Card drivers

24
Q

Describe BIOS

A

Stands for Basic Input Output System

Stored in ROM

Performs the Power On Self-Test (Tests hardware is working)

Stores the Bootstrap loader (used to boot up the OS)

Can change settings such as which storage device the computer boots from.