gcse computing revision: a451 written exam. - jfcs.org.uk hardware keywords keyword definition cpu...

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A451 GCSE Computing | Hardware| Required knowledge

It is your responsibility to make sure you regularly revisit this knowledge outside of class.

Hardware- Definition.

- Components

- Input

- Process

- Storage

- Output

- Computer architecture

- Von Neumann

Binary logic- Why do computers use binary values?

- Logic gates

- Truth tables

Output devices

- Monitor

- Printer

- Plotter

- Speakers

- Actuators

Central processing unit (CPU)- Arithmetic & logic unit

- Control unit.

- Fetch-execute cycle

- Fetch

- De-code

- Execute

- The boot sequence

- Clock speed

- Processor speeds (MHz, GHz)

- Cache memory

- Multiple processor cores

- Advantages / disadvantages.

Memory- Random Access Memory (RAM)

- Volatile

- Read Only Memory (ROM)

- Non-volatile

- Virtual memory

- Flash memory

Input devices

- Keyboard

- Mouse

- Touch screen

- Microphone

- Camera

- Sensor

- Bar code scanner

- Eye-typer

- Foot mouse

- Puff-suck switch

- Braille keyboard

Secondary storage

- Magnetic hard disk

- Optical disk

- Flash memory

- Considerations for selecting

storage:

- Capacity

- Speed

- Portability

- Durability

- Reliability

John Von Neumann

Hardware keywordsKeyword Definition

CPU Central processing unit - processes program instructions. Also called a microprocessor.

Fetch-execute cycle Process by which a computer processes instructions.

Clock speed The speed of a computer CPU, measured in hertz. The number of times a second acomputer carries out the fetch-execute cycle.

Core A processing unit within a CPU. CPUs can have multiple cores.

Storage The hardware of a computer that stores data long term, such as a memory card or hard drive.

Memory The part of a computer that stores data.

Cache memory A piece of temporary memory. It can refer to a part of the RAM, storage disk, CPU, or an area for storing web pages.

RAM Memory that is constantly being written to and read from. It does not retain its contents without a constant supply of power, ie when a computer is turned off, everything stored in its RAM is lost.

Volatile memory It does not retain its contents when the power is switched off.

ROM Memory or storage that has data stored on it that cannot be changed, i.e.

Non-volatile memory It does retain its contents when the power is switched off.

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

Hardware keywords from memory.Keyword Definition

CPU

Fetch-execute cycle

Clock speed

Number of cores

Storage

Memory

Cache memory

RAM

Volatile memory

ROM

Non-volatile memory

Virtual memory

Past paper exam questions.2011 past paper.

Past paper answers.2011 past paper.

Notes: What do I need to improve?

Software keywords

Keyword Definition

System software Controls the hardware, e.g. operating system.

Application software Handles the real world jobs that users want to do, e.g. word processor.

Utility software Has limited functionality and is used to maintain computers, e.g. Antivirus.

Operating system Set of programs that controls hardware & lets users and applications work with the computer.

Defragmentation Used to tidy up disks by storing parts of files next to each other.

Disk clean-up Searches for unused files and clears them out.

Virtual memory When a computer uses secondary storage to temporarily act as RAM.

User interface Boundary between the human user and machine.

Authentication Check that users are who they say they are, e.g. username / password.

Privileges Rights assigned to users and groups, e.g. read / write / read & write.

Open source software Software placed in the public domain – access to source code.

Custom written software Software commissioned for a specific purpose.

Proprietary software Software developed for profit. Source code retained and kept secret.

Off the shelf software Bought from a shop and ready to install, e.g. MS Office or Windows.

Software keywords from memory

Keyword Definition

System software

Application software

Utility software

Operating system

Defragmentation

Disk clean-up

Virtual memory

User interface

Authentication

Privileges

Open source software

Custom written software

Proprietary software

Off the shelf software



2011 past paper answers.

Past paper exam questions.

2012 past paper. 2012 past paper answers.


Past paper exam questions.

2013 past paper. 2013 past paper answers.


A451 GCSE Computing | Data representation| Required knowledge


Numbers- Binary – base 2.

- Denary – base 10.

- Converting from binary to denary.

- Converting from denary to binary.

- Adding binary numbers.

- Overflow error

- Units.

- Nibble

- Byte

- Kilobyte

- Megabyte

- Gigabyte

- Terabyte

Hexadecimal (hex) numbers- Hex – base 16

- Converting between hex and

denary.

- Converting between hex and

binary.

Characters- Character set.

- Definition

- ASCII

- Unicode

Images- Stored in binary on a computer.

- Metadata

- Pixel

- Colour depth

- Resolution

- Bitmap images

- Vector images

Sound- Metadata

- Sample rate

- Quality of sound

- File size

- Sample interval

- Bit rate

Instructions- Fetch-Execute cycle

- Op-code

- Operand

- Accumulator

Data representation keywordsKeyword Definition

Binary (base 2) A number system that contains two digits, 1 & 0 (also known as base 2).

Denary (base 10) The number system most commonly used by people. It contains 10 unique digits 0 to 9. Also known as decimal or base 10.

Hexadecimal (base 16) A number system using 16 characters from 0 to 9 and A to F, also known as hexadecimal.

Character set A complete collection of characters.

ASCII A 7-bit set of codes that allows 128 different characters. That is enough for every upper-case letter, lower-case letter, digit and punctuation mark on most keyboards.

Unicode Unicode uses between 8 and 32 bits per character, so it can represent characters from languages from all around the world. It is commonly used across the internet.

Image resolution (images) The fineness of detail that can be seen in an image - the higher the resolution of an image, the more detail it holds. It is measured in dots per inch (dpi).

Colour depth (images) The colour depth of an image is measured in bits. The number of bits indicates how many colours are available for each pixel.

Sampling interval (sound) Time between samples being taken. The higher the sample interval, the lower the sample rate.

Sampling rate (sound) How many samples of data are taken per second. This is normally measured in hertz, eg an audio file usually uses samples of 44.1 kHz (44,100 audio samples per second).

Operand (data) Data that is manipulated by opcodes in a CPU machine code instruction set.

Op-code (instruction) Specifies instructions that can executed by a CPU in machine code.

Meta-data Metadata means 'data about data' and provides information about the image, e.g. file format, colour depth, resolution, e.t.c.

Data representation keywords from memory

Keyword Definition

Binary (base 2)

Denary (base 10)

Hexadecimal (base 16)

Character set

ASCII

Unicode

Image resolution (images)

Colour depth (images)

Sampling interval (sound)

Sampling rate (sound)

Operand (instructions)

Op-code (instructions)

Meta-data


Exam tip: When converting numbers in exam questions make sureyou show your workings.

Database keywordsKeyword Definition

Database Persistent organised store of data.

Entity Something in real life about which we store data.

Table Where data is organised and stored in a database.

Primary key Uniquely identifies a record.

Foreign key A reference to a primary key in a relational database table.

Flat file database A database that stores data in a single table.

Relational database A database that stores data in multiple tables that are linked together.

Validation Process of checking data as it is being input, e.g. length check.

Verification Checking that data is correct.

DBMS (Database management system)

A tool to store, edit and organise a database.

Data redundancy Unnecessary repetition of data.

Database keywords from memoryKeyword Definition

Database

Entity

Table

Primary key

Foreign key

Flat file database

Relational database

Validation

Verification

DBMS (Database management system)

Data redundancy

Past paper answers.2011 past paper. Notes: What do I need to improve?


Long answer question.

@CES_teach

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A451 GCSE Computing | Networks | Required knowledge


Network hardware- Network interface card (NIC).

- Cables- Unshielded twisted pair (UTP)

- Fibre-optic

- Hub

- Switch

- Wireless access point

- Router

Types of network- Client-server network.

- Peer-to-peer network.

Network topologiesDiagram, advantages and

disadvantages of the following:

- Bus

- Ring

- Star

Network technicalities.- Protocols

- TCP/IP

- Data packets

- Domain Name System (DNS)

- File Transfer Protocol (FTP)

- Hypertext Transfer Protocol

(HTTP)

- Packet switching

- IP addressing

- MAC addressing

Network security- Backups

- Archives

- Failover

- Disaster recovery

- Authentication

- Acceptable use policies

The internet.- The internet vs. World Wide

Web

- Hardware- Modem

- Router

- Addressing- Uniform Resource Locator

(URL)

- IP address

- Domain name System (DNS)

- Hypertext markup language

(HTML).- Cascading style sheets (CSS)

Internet file standards.- Meaning and uses for each of

the following:- JPG

- GIF

- PDF

- MP3

- MPEG

- Compression

- Lossy

- Lossless.

Networks- Collection of connected

computers.

- LAN

- WAN

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‘Networks’ keywords

Keyword Definition

Topology Arrangement of various elements of a computer network.

Client-server network Services / applications are hosted on a central server and accessed via client computers.

Peer-to-peer network All computers on the network have equal status – no central server.

Router Device for connecting computers together to form a network.

Server A computer that holds data to be shared with other computers.

Switch Intelligent device – used to connect computers together. Sends packet of data to requested computers.

Network Interface card (NIC) Needed in order for a computer to connect to a network.

MAC address Media Access Control – each piece of hardware on a network has a unique MAC address.

IP address Numerical address assigned to each device that connects to the internet.

Domain Name System (DNS) Internet service that translates domain names into IP addresses.

HTML Hyper Text Markup Language – used to write and display web page documents.

Protocol A set of rules for how messages are turned into data packets and sent across a network.

Lossy compression Reduces the file size by permanently deleting redundant information.

Lossless compression Every bit of data remains in the file when it is uncompressed.

Networks - keywords from memory.

Keyword Definition

Topology

Client-server network

Peer-to-peer network

Router

Server

Switch

Network Interface card (NIC)

MAC address

IP address

Domain Name Server (DNS)

HTML

Protocol

Lossy compression

Lossless compression

A451 GCSE Computing | Programming | Required knowledge


Algorithms.- Flowcharts

- Symbols

- Pseudo-code

- Written English.

- Use of indentation.

Programming languages.- Low level languages:

- Machine language

- Op-code

- Operand

- Assembly language

- Mnemonics

- High level languages:

- Source code

- Assembler

- Compiler

- Interpreter

Integrated development environment

(IDE).- Source code editor.

- Error debugger.

- Run time environment.

- Translator (compiler or interpreter).

- Automation tools

- Auto-complete code.

- Auto-complete documentation

Control flow- Sequence

- Selection

- IF… ELSE…

- Iteration

- For

- While

Data types- Integer e.g. 23

- Real e.g. 23.7

- Character e.g. A or 5

- String e.g. A546TH

- Boolean e.g. TRUE or FALSE.

Variables & constants- Named storage space reserved in

memory.

- Both declared.

- Definition of variable.

- Definition of constant.

Operations- ADD +

- SUBTRACT –

- DIVIDE /

- MULTIPLY *

- MOD

- DIV

Comparison operators

- Operator priority: BIDMAS

Comparisonoperator

Meaning

= or == Is equal to

> Is greater than

< Is less than

<> or != Is not equal to

>= Greater than or equal to

<= Less than or equal to

Data structures- Arrays

- Definition

- Example

Testing- Test data should be chosen to

cover valid, invalid, extreme &

erroneous situations.

- Logic errors

- Definition & examples.

- Syntax errors

- Definition & examples.

Programming keywordsKeyword Definition

Algorithm A sequence of logical instructions for carrying out a task. In computing, algorithms are needed to design computer programs.

High level programming language

A computer programming language used to write programs. They need to be translated into machine code through a compiler, interpreter or assembler.

Low level programming language

Low-level language is a programming language that deals with a computer's hardware components

IDE (Integrateddevelopment environment)

Integrated development environment - a piece of software used to write computer programs.

De-bugging The process of finding and correcting programming errors.

Sequence In computer programming, this is a set of actions that follow on one from another.

Selection A decision within a computer program when the program decides to move on based on the results of an event.

Iteration In computer programming, this is a single pass through a set of instructions.

Variable In a computer program, this is a memory location where values are stored.

Constant A value in computer programming that does not change.

Compiler A special program that processes statements written in a particular programming language and turns them into machine language or "code" that a computer's processor uses.

Interpreter A computer program that directly executes, i.e. performs, instructions written in a programming or scripting language, without previously compiling them into a machine language program.

Programming keywords from memoryKeyword Definition

Algorithm

High level programming language

Low level programming language

IDE (Integrateddevelopment environment)

De-bugging

Sequence

Selection

Iteration

Variable

Constant

Compiler

Interpreter

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