Ocr Computer Science Revision

Front 1

What is the ALU?

Back 1

The ALU or Arithmetic logic unit, performs
arithmetic and logical operations.

These can be found in CPUs and GPUs.

Front 2

The CPU is made up of 3 parts, what are they?

Back 2

Control unit, Immediate Access Storage and
the ALU.

Front 3

What is the function of the Control Unit?

Back 3

Extracts instructions from memory and decodes and executes them.

Front 4

What is the F-D-E?

Back 4

Fetch, decode, execute. This is when the CPU fetches the instruction, stores in in the IAS, then it is decoded to machine code and executed to carry out the operation.

Front 5

Where does the CPU fetch instructions from?

Back 5

The Random Access Memory (RAM).

Front 6

What 3 things might you find stored in Memory?

Back 6

Instructions, Commands, operating
systems, software and utilities.

Front 7

What does ROM stand for and what does it do?

Back 7

- Read Only Memory

- The boot files for the computer

-Non-Volatile

-Flash Memory, Quick Access

Front 8

Name 2 differences
between RAM and ROM?

Back 8

- Ram is Volatile

- ROM is Non-Volatile

- RAM change frequently

- ROM never changes

Front 9

When referring to
computer memory what is meant by Random Access?

Back 9

You can write anywhere in that memory space at any time.

Front 10

When discussing memory what is meant by volatile?

Back 10

It requires power and loses its content if there is no power.

This is usually RAM.

Front 11

What is virtual memory?

Back 11

A part of the hard drive used as memory when memory has become full.

Front 12

When would you need to use virtual memory?

Back 12

A section of a computer storage drive which is temporarily used as RAM.

Front 13

What does 3MGz mean and what is Over-Clocking?

Back 13

It is the Clock Speed of the computer, it can
complete 3 million cycles per second.

Over-Clocking is the process of pushing the speed and power over the hardware limit.

Front 14

What is Cache Memory and How does cache size affect the performance of a
computer?

Back 14

The Cache stores future requests and
instructions to be executed.

The larger the size of the cache, the more

instructions can fit, the quicker the CPU can
process the instructions.

Front 15

Multi-Core Processers?

Back 15

The computer has 2+ separate cores, which are each capable of running cycles.

This is so more cycles can be run
simultaneously.

Front 16

NOT (1) =

Back 16

0

Front 17

1 AND (NOT 1) =

Back 17

0

Front 18

1 OR ( 1 AND (NOT 0)) =

Back 18

1

Front 19

What is a bit?

Back 19

A single 1 or 0

Front 20

What is a byte?

Back 20

8 bits

Front 21

How does having more RAM improve the
performance of a
computer?

Back 21

It can load more programs and data at the same time, but only if the instructions to boot them are stored.

Front 22

What is optical storage?

Back 22

CDs and DVDs.

Front 23

What does DVD stand for?

Back 23

Digital video Disc

Front 24

Who might use Flash Memory and why?

Back 24

Anyone who needs to transfer data from one place to another and can access it quickly, but keep it small enough to transport easily.

Front 25

What type of memory does a USB stick use?

Back 25

Flash memory.

Front 26

What does the SD stand for in SD card?

Back 26

Secure digital, Card

Front 27

What does the RW stand for in DVD-RW?

Back 27

Re-writable.

Front 28

What is the difference
between a DVD-R and a DVD-RW?

Back 28

DVD-R can only be written once.

Front 29

What is a solid state drive?

Back 29

A form of flash memory, portable storage that does not use magnetic tape like a HDD.

Front 30

What is cloud storage?

Back 30

Online storage.

Front 31

What is an input device?

Back 31

A device used to transfer data into the computer
system.

Front 32

What is an output device?

Back 32

A device that displays or communicates the
processed data.

Front 33

What input devices would a central heating

system use?

Back 33

Temp sensor
(thermometer), timer, dial, keypad.

Front 34

Name 2 features of a hard drive.

Back 34

Large capacity, fairly cheap, magnetic storage, not

portable.

Front 35

Name 2 features of a
CD-ROM.

Back 35

Small and portable, can be used on most devices.

Front 36

Name 2 features of a solid state drive.

Back 36

Very portable, good for

carrying work.

Front 37

Give an example of

magnetic storage.

Back 37

Hard drive, magnetic tape.

Front 38

State functions of an operating system.

Back 38

- Provides a GUI.

- Provide a platform for applications to run.

- Perform memory management.

-perform file/disk management.

Front 39

Name some Operating Systems

Back 39

Windows, iOS, Android, Linux, Ubuntu.

Front 40

Name Utility programs

and their uses.

Back 40

System Clean-up - Searches + deletes files/
programs which are no longer used.

Automatic Update - Checks the Internet for new versions of programs which are installed.

Disk defragment - cleanup the hard drive, move files, Anti Virus.

Front 41

Give an example of

off-the-shelf software.

Back 41

Excel, Access, Word etc.

Front 42

Two features of
open-source software.

Back 42

- Is free to use

- lots of people contribute to it

- Doesn't need a license

Front 43

What is a pixel?

Back 43

The smallest element of an image – dots that make up an image on a screen.

Front 44

How many bits does ASCII use?

Back 44

7 or 8 bits (either is right)

Front 45

How many bits does Unicode use?

Back 45

16 or 32 bits (either is right)

Front 46

Why do we use
compression when sending files over the Internet?

Back 46

Reduce transmission times + save storage space.

Front 47

What type of software is needed for a computer to communicate with a device such as a printer?

Back 47

Device driver/driver
software

Front 48

Assembly language is also known as…

Back 48

A low level language.

Front 49

In what language do

mnemonics make an
appearance?

Back 49

Assembly language

Front 50

What language do
machines understand?

Back 50

Binary/Machine language

Front 51

Features of an IDE.

Back 51

- Source code editor

- Error diagnostics and debugger

- Run-time environment/translator

Front 52

A sequence is when…

Back 52

Instructions are executed one after the other.

Front 53

Selection is when…

Back 53

The path through the
program is decided by looking at a condition (IF statement).

Front 54

Iteration is when…

Back 54

The programs repeats commands until a critieria has been met (Loop).

Front 55

What is the difference
between a FOR loop and a WHILE loop.

Back 55

With a FOR loop we know how many times the loop will run before the code is run, with a WHILE loop the user can choose to stop the loop or keep repeating.

Front 56

What is the difference

between a variable and a constant?

Back 56

A variables value can change in the program, a constant cannot change.

Front 57

Define an Array

Back 57

A set of variables with the same name

(identifier).

Front 58

What is a variable?

Back 58

An identifier that points to a place in memory.

Front 59

What is a syntax error?

Back 59

A mistake which breaks the grammar of the

programming language.

Front 60

What is a logic error?

Back 60

The program will run,
however it does not give you the result you
expected.

Front 61

What is a Program

Counter?

Back 61

A register that contains the instruction address,
awaiting execution.

Front 62

What is the Accumulator?

Back 62

A register in which

intermidiate arithmetic and

logic results are stored.

Front 63

What is the (MAR) Memory Address Register?

Back 63

Memory section which
contains the address of
future fetched instructions.

Front 64

What is the Memory Data Register?

Back 64

A Register of a computers control unit that contains data to be stored in the computers storage.

Front 65

What is the Current Instruction Register?

Back 65

Storage for current

decoding or executing

instructions.

Front 66

What is Pipelining and how does it work?

Back 66

It is the operation of a sequential order of execution, so after one executed, the next one begins.

Front 67

What is Thrashing?

Back 67

This is when a HDD is over-worked by moving

information between system Memory and

Virtual Memory excessively.

This affects the performance speed of the

system, and more RAM should be added to fix this.

Front 68

Primary vs. Secondary Memory

Back 68

Primary Memory is the area in a computer in which data is stored for quick access by the
computer's processor. (RAM)

Secondary memory is where programs and data are kept on a long-term basis. Common
secondary storage devices are the hard disk and optical disks.

Front 69

What is Paging?

Back 69

It is a way of using virtual memory to find and use data immediately when needed.

Front 70

Von Neumann Architecture
Advantages and Disadvantages

Back 70

Advantages:

- Flexible between instructions and data that

occupy the same memory.

- The organisation of this memory is in the handsof programmers.

Disadvantages:

- Thewhole execution process is slower

-One bus is a bottleneck and so only one set of

information can be access at the same time.

Front 71

Harvard Architecture

Back 71

Uses physical separate storage and signal
pathways for instructions and data.

Front 72

Harvard Architecture

Advantages and Disadvantages

Back 72

Advantages:

- Allows parallel access between the two
memories.

- Both the data and instruction are accessed inthe same way.

Disadvantages:

- Free memory cannot be used for instructions.

- Expensive to build and develop.

Front 73

CISC vs. RISC

Part 1

Back 73

CISC stands for Complex
Instruction Set.

Computers and RISC stands for Reduced Instruction Set
Computer.

Front 74

CISC vs. RISC

Part 2

Back 74

CISC:

- Has more complex hardware

- More complicated software code

RISC:

- Has simpler hardware

- More compact software code

Front 75

GPUS (Graphic Processing Unit)

Back 75

A specialized electronic circuit designed to

rapidly manipulate and alter memory to

accelerate the creation of images in a frame buffer intended for output to a display.

Front 76

What is Segmentation?

Back 76

Memory segmentation is the
division of a computer's primary memory into segments or

sections.

Front 77

Buffers and Interrupts

Back 77

Buffers are a section of physical memory
storage which is used to store data while it is being moved from one place to another.

Interrupts are a type of signal of which calls the attention over of the CPU to thehardware
immediately.

Front 78

Stacks and Queues

Back 78

Stack are Last in, First Out and Queues are Last in, Last Out.

Front 79

Types Of Operating Systems

Part 1

Back 79

Real Time- Managing the resources of the

computer so that a particular operation

executes in precisely the same amount of time, every time it occurs.

Single User- This type of operating system only has to deal with one person at a time, running one user application at a time.

Front 80

Virtual Machines

Back 80

A virtual machine is an emulation of a

particular computer system. Virtual machines operate based on the computer architecture and functions of a real or hypothetical computer, and their implementations may involve

specialized hardware, software, or a

combination of both.

Front 81

Application Software

Back 81

Application software can be divided into two general classes: systems software and

applications software. Applications software include such things as database programs, word processors, Web browsers and spreadsheets.

Front 82

Stages of Compilation

Back 82

1. Source program preprocessing

2. Source program compiling

3. Assembly program assembling

4. Machine instructions linking

5. Executable code

Front 83

Compiler

Back 83

The Compiler is a computer program which scans the entire program at one time and then coding into machine code. Then the
computers processor executes the program.

Front 84

Interpreter

Back 84

The Interpreter first converts higher level
language into an intermediate and scans the program line by line and suddenly stops, then shows errors and doesn't scan further.
E.g. Languages like MATLAB, Ruby uses
Interpreters.

Front 85

Assembler

Back 85

Assemblers are used to convert lower level
language into the machiner code and
usually used in micro processor.

Front 86

Linker

Back 86

A linker or link editor is a computer program that takes one or more object files generated by a compiler and combines them into a single
executable file, library file, or another object file.

Front 87

Loader

Back 87

A simpler version that writes its output directly to memory is called the loader, though
loading is typically considered a separate
process.

Front 88

Programming Paradigms

Back 88

A programming paradigm is a style or “way” of programming. Some languages make it easy to write in some paradigms but not others.

Front 89

Procedural Languages

Back 89

Procedural language is a type of computer
programming language that specifies a series of well-structured steps and procedures within its programming context to compose a program.

Front 90

Assembly
Language (LMC)

Back 90

A low-level symbolic code converted by an

assembler.

Front 91

Object-Oriented

Languages

Back 91

Simula was the first object-oriented
programming language. Java, Python, C++, Visual Basic.NET and Ruby are the most popular OOP languages today.

Front 92

Lossy and Lossless

Compression

Back 92

Lossless compression means that as the file size is compressed, the picture quality remains the same - it does not get worse.

Lossy compression permanently removes data.

Front 93

Hashing

Back 93

Hashing is the transformation of a string of characters into a usually shorter fixed-length

value or key that represents the original string.

Front 94

Relational Database

Back 94

A database which can have it's tables linked to limit referential integrity and use the data from one, in another.

Front 95

Flat File

Back 95

A flat file database is a database which, when not being used, is stored on its host computer system as an ordinary, non-indexed "flat" file.

Front 96

Primary Keys, Foreign Keys and Secondary Keys

Back 96

A primary key is a key in a relational database that is unique for each record.

A foreign key is a field in one table that
uniquely identifies a row of another table.

Secondary Keys are an entity may have one or more choices for the primary key.

Front 97

Entity Relationship,

Normalisation and

indexing

Back 97

An entity relationship modelis a graphical
representation of entities and their
relationships to each other.

Normalisation is the process of organizing the columns and tables of a relational

database to minimize data redundancy.

Indexing is the process of entering

information from historical records into an online, searchable database.

Front 98

Referential Integrity and Data Redundancy

Back 98

Referential Integrity is the process of stopping the loss of data from the users actions.

Data redundancy is a condition created within a database in which the same piece of data is held in two separate places.

Front 99

Network Protocols

Back 99

TCP – Transmission Control Protocol; used withIP to ensure error free transmission and package switching.

IP – Internet Protocol; used to transfer
allpackets across the internet between
routers.

FTP – File Transfer Protocol; Used by
clientsand servers to upload and download files across the internet.

HTTP – Hypertext Transfer Protocol; Used by webservers and browsers to transfer web
pages.

SMTP – Simple Mail Transfer Protocol; Used bymail servers and clients to transfer email across the Internet.

Front 100

Topologies and Network Types

Back 100

Topologies are way of connecting devices
within a network.

WAN:

- Wide Area Network

- Covers a large geographical area- might beworldwide

- Telecom companies may own the networkinfrastructure

VPN:

- Virtual Private Network

- Piggybacks the internet for infrastructure

- This is therefore a need to make this highlysecure

Other Networks:

SAN – Storage Area Network, Data storage centres

MAN – Metropolitan Area Network, providesnetworks in cities

PAN – Personal Area Network, Link personal devicessuch as phones + tablets.

Front 101

Packet Switching +
Circuit Switching

Back 101

Circuit switching:

- Two network nodes establish a dedicated communicationschannel through the network before the nodes may communicate.

- Follows one direct route

- From node to node

Packet Switching:

- Data broken down into packets

- Packets take a different route each

- Each packet has a sequence number

- This is a more efficient way

Front 102

IP and MAC Address

Back 102

IP (Internet Protocol):

- A numerical label assigned to each device

- Participating in a computer network that uses the- Internet Protocol for communication

Two principal functions:

-Host or network interface identification

-Location addressing

MAC Address:

- MAC addresses are used as a network
address.

- Assigned to network interfaces for
communications on the physical network
segment.

Front 103

Client Vs. Peer to Peer

Back 103

Peer to Peer:

-All the same status

-Slow data transfers due to collisions and shared process power

-Suitable for small and low air traffic

-Designed for the home.

Client Server:
- At least one computer is a designated server.
- Needs to be high spec
- Manages traffic on the network
- Records what people do
- Gives security
- Clients have to sign in
- Large networks can be used to handle increasing demands
- Client requests services from server.
- Large Networks have a specialised server.