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A-Level Computer Science OCR > Software > Flashcards

Flashcards in Software Deck (119)
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1

When are interrupts checked for

at the end of each FDE cycle

2

Uses of virtual machines

- used on networks to avoid redundant processors
- translating code (Java)
- running different operating systems

3

boot up process of a computer

- POST is run
- clears anything in the registers
- loads the address of the first instruction of the boot program into the PC
- the boot program checks for start-up instructions on the BIOS
- The OS kernel is loaded

4

Uses of Embedded operating systems

Washing machines, vending machines, car engine systems, traffic lights, pay and display machines

5

Uses of Multi-tasking operating systems

desktops and smart phones

6

Uses of real-time operating systems

Airline control, theatre bookings, heart monitors, production lines, radar systems

7

Uses of Multi-user operating systems

schools and offices

8

Use of distributed operating systems

Data centres, large companies, weather/financial modelling, data mining trend finding

9

functions of an OS (8)

- Provides a user interface
- manages security
- provides a platform for utilities/applications
-manages external devices
- managing the processor/scheduling
-managing memory
- provides a platform for networking
- managing hardware

10

How does Java use virtual machine?

the virtual machine execute intermediate code (Java Byte code)

11

Device drivers are...

hardware dependent and OS specific

12

Multi-level feedback queue

uses multiple queues based of the priority of the process.

13

Non pre-emptive algorithms

- First come first serve
- shortest job first

14

Pre-emptive algorithms

- Round Robin
- Shortest Remaining Time
- Multi-level feedback queue

15

Pre-emptive

Once a process has entered the running state it can be stopped

16

Aims of scheduling

- to provide an acceptable response time to all users
- To maximise the time the CPU is usefully engaged
- To ensure fairness on a multi-user system

17

What happens if an interrupt is detected?

- the contents of all the registers are pushed onto a stack
- The interrupt service routine is run
- Once complete the values of the registers are popped off the stack back into the registers

18

What does an OS provide?(4)

- User interface
- Memory Management
- Interrupt handling
- Processor scheduling

19

What loads the OS into RAM

the bootloader

20

Library Programs (System Software)

contains useful functions that are frequently used by programs. Simplifies the process of application development.

21

Operating system (System software)

software that allows the user to control the computer with ease. It provides a virtual machine hiding the true complexity of the computer from the user and manages and controls access to the computer's resources.

22

examples of system software

Operating system, Utility Program, Library Program, Translators.

23

system software

operates, controls and maintain the computer and its components.

24

Hardware

the physical components of the computer system.

25

Software

program code. Sequences of instructions which are executed in order to perform a task.

26

Backing Up

programs which allow for manual or automatic backing up of files onto another disk, on the existing computer system, to a removable device such as DVDs or CDs, to a network file server or to a cloud based storage system online

27

Firewalls

a program that blocks unauthorised access onto a network by inspecting packets to find the port they are attempting to access through.
If the port is blocked then the packet is rejected.

28

file managers

programs which allow users to easily copy, delete, rename and modify files on a computer system

29

compression

programs which attempt to reduce the amount of physical space that files take up when they're stored

30

fragmented disk

over time a disk becomes fragmented as old files are deleted and new files are added, free space often becomes scattered across a disk and a program has to be split and spread across a disk to fit. The more fragmented the slower the computer performs