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126 Cards in this Set
- Front
- Back
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Fixed loop |
A fixed loop is a loop that repeats the same number of times each time it is run. An example of a fixed loop is a FOR..NEXT loop
FOR counter = 1 to 10 Print counter * 5 NEXT counter |
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Conditional loop
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A conditional loop is code that repeats until a particular condition becomes true. An example would be a LOOP UNTIL loop.
SET computerguess TO 6 DO Ask for guess LOOP UNTIL guess = computerguess |
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Conditional Statement (IF)
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A conditional statement is a block of code that only executes if a condition is met. This is usually an IF statement.
IF total > 50 THEN SET numover50 TO numover50 +1 END IF |
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String
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String is a data type in a program. A string contains text characters and numbers (e.g. Hello123, Monkey, 45percent, Braes)
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Integer
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An integer is a whole number (one without a decimal point)
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Normal, extreme and exceptional tests
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Test data for numberic input can be divided into normal, extreme and exceptional tests.
A program that should only accept numbers between 1 and 100 would have the following test data: -Normal: any number between 1 and 100 -Extreme: Only 1 and 100 (the extremes of the range) -Exceptional: -5, 0, 101 and 105 |
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Readability
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A readable program has the following:
* Indentation - blocks of code are pushed in from the left of the page to make it clear that they are grouped, for example: IF something = 29 THEN Set something_else to 40 END IF * Meaningful variable names - variables should be named after what they store, such as total, score or name. * Comments (also known as internal docmentstion) - notes in English written into the code to make it easy to understand. |
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Pre-defined function
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A pre-defined function is code included with a programming language to carry out a common task, such as rounding a number, providing a random number or finding the length of a string.
e.g. RND ASC mid$ |
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Boolean
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Boolean is a data and field type that can store the value 0 or 1 (representing true or false, or yes and no)
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Difference between variable and array (which is a data structure)
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A variable can store one item of data.
An array (is a data structure) that can store a list of items of data. An array is a data structure (the only one you need to know at N5) |
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Syntax errors
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A syntax error is caused by a missing character or keyword in a program, such as misspelling a command (PINT instead of PRINT) or missing a keyword (like END IF)
Syntax errors prevent your program from running |
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Execution (or run-time) errors
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An execution error is an error that occurs while the program is running. This can crash the program.
Execution errors can be caused by dividing a number by zero or using a number that is so big that the computer cannot store it. |
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Logic errors
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"A logic error is an error in a program where the programmer has written code that runs but does not do what is was designed to do.An example of a logic error would be the use of the statement ""IF num>1 and num<10"" to test for numbers between 1 and 0 (this code tests for numbers between 2 and 9)."
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Input validation
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Input validation is a check on data. This means that when a user inputs a value, the program will not continue until the data has been checked and is correct. An example of input validation would be a password screen - if the password is incorrect, the screen will continue to appear.
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Structure diagram
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A structure diagram is a diagram that represents the design of a program by using boxes for each section.A structure diagram has a main box with the name of the program on one line, then a box with all sub steps for a program on the line below. The boxes on the second line are connected to the box at the top with a line.On the third row, sub steps of each of the boxes on the first row can be added, and so on, until the program design is detailed.
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Flow chart
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A flow chart is a diagram that demonstrates the pathways of a program. In a flowchart, input, loops and conditional statements are clearly displayed to make it easy to trace through what would happen when an item of data is entered into a program.
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Pseudocode
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Pseudocode is a method of designing a program. Pseudocode uses lines of English to describe the steps in a program. It allows designers to write and structure code (including IFs, loops etc) without picking a language.
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Interpreter
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An interpreter translates HLL into machine code one line at a time, as the program runs. This slows down the rate that the program code is executed, and means that the interpreter must run every time the user wants to use the program.
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Compiler
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A compiler translates a high level language program into machine code by converting all lines in one process. This produces a machine code copy. A compiler is only run once - the machine code is run directly after it has been produced.
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Difference between interpreters and compilers
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Interpreters translate code from HLL to machine code line by line, as it runs. An interpreter must always be running when code is being translated, which slows the program down.
Compilers translate all HLL into machine code in one go. The machine code is dumped to a file, which is run after translation. This means the compiler is needed once. |
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Binary numbers
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A binary number consists of 1s and 0s.
Each 1 and 0 has a place value. The binary number 10000011 is the number 131 in decimal. This can be worked out by writing down the place values (128, 64, 32, 16, 8, 4, 2, 1) and writing the 1s and 0s underneath. To convert the binary number to decimal, add up the columns with 1 underneath. 128 + 2 + 1 is 131. Binary is used by computers because computers use electrical signals which are either on (1) or off (0) |
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Bitmap graphics
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Bitmap graphics are graphics stored as a grid of pixels. Each pixel has a colour. The number of colours is determined by the number of bits used to store each pixel.
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Vector graphics
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Graphics stored using a set of instructions describing a shape, e.g.:
Xposition: 50Yposition: 50Height: 100Width: 100Colour: Red |
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Three parts of a processor
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Arithmetic and Logic Unit Control UnitRegisters
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Data bus
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The data bus transfers data from the processor to memory and from the memory to the processor. The data bus is bidirectional.
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Address bus
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* The address bus transfers the location of an item of data from the processor to the memory
* This allows the computer to read from a location or write data to a location in the computer's memory. |
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Interface
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An interface is an device which connects a device to the computer's processor. USB, Firewire, SATA and Wifi all act as interfaces.
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Flat file database
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A flat file database is a database that consists of information about different subjects contained within a single record. This means that some of the information must be duplicated.
For example, if each pupil in the school had the name of their registration teacher listed on their pupil record, this would mean that the teacher's name would be entered for every pupil in their class. The alternative would be to link the pupil's record to records containing teachers and classes. |
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Linked tables
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Tables in a database can be linked using a primary key and foreign key. Each item in one table may have a relationship with an item in another (for example, a list of orders could be linked to a list of people that made orders).
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Primary key
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A primary key is a field that uniquely identifies a record.
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Foreign key
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A foriegn key is a field that has been added to a record to link it to another table. The foreign key is the primary key in the other table.
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Field types (text, number, date, time, graphic, calculated, Boolean)
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In a database the following field types are used:
Text : characters Number : Any number, formatted by the database to suit. Date Time Graphic Calculated: a field that generates its value from other fields Boolean: True or False/Yes or No |
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Validation types
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Presence check, restricted choice, field length, range check
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URL
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Uniform Resource Locator.The unique address of a web page.
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Difference between internal and external hyperlinks
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Internal hyperlinks are part of the current website. External hyperlinks link to another website.
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Relative and absolute addressing of web pages
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Relative web page addresses are links that only use part of an address. This is because the rest of the address will be the same domain and directory (e.g. example.com/folder ) as the current web page.Absolute web page addresses are full addresses, and start with http:// (e.g. http://www.yahoo.com/index.html )
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Web browser
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Software that fetches and displays web pages
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Search engine
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A search engine is a web site that allows users to enter keywords to find matching web pages.
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Text files
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Text files are files that store plain text. This means that a text file contains ASCII characters, with no mark-up or style information stored.
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RTF files
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RTF files are Rich Text Format file. They are documents that store text styles and font selections. RTF is a standard file format that can be loaded by a variety of applications.
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Compression
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Compression is the process of shrinking a file to a smaller size. This means the file takes less storage and can be transferred to other computers in less time over a network.
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Calculating the size of an image
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To calculate the size of an image:
1) Find the number of pixels in the image by multiplying the width in pixels times the height in pixels. If the width and height are in inches, convert them to pixels by multplying them by the dots per inch given. 2) Multiply the number of pixels by the number of bits used to store each pixel (the bit depth). If the number of colours used is given instead, you must work out how many bits are used for the number of colours (for example, 256 colours require 8 bits per pixel) 3) Convert to appropriate units (divide by 8 for bytes, then 1024 for KB, MB, GB) |
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Difference between scripting language and mark-up language
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Scripting languages are programs used to change the contents of pages such as web pages (e.g. Javascript)
Mark-up languages decribes the contents of a page (e.g. HTML). |
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Tests to carry out on a website
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Web site tests can be carried out by simulating the user experience. Tests should include clicking links, checking the elements of a page load, and checking that items on page update (e.g. hit counters)
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Input devices
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Input devices are devices that send data to the computer for controlling the computer or capturing data. Input devices include the mouse, keyboard, webcam, scanner and microphone.
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Output devices
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Output devices are used to receive data from the computer. Output devices include printers, monitors and speakers.
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Processor speed
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Processors are the chips in computers that perform all the computing work in a computing device. The main memory will store the data processed by the processor. Processor speed is measured in Hertz, usually in groups of 1 billion (1 Gigahertz = 1,000,000,000 Hertz). One Hertz is one pulse of the computer's clock, which is the time given for each instruction.
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RAM
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RAM stands for Random Access Memory. RAM is rewritable computer memory that can be accessed at any location using an address. RAM stores the data and applications that a computer is using. When the computer is switched on, it transfers important data and programs to RAM. When it is switched off, RAM is wiped.
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ROM
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ROM stands for Read Only Memory. ROM is memory that has been written in a factory. It is not writeable.ROM is usually used to store startup code for the computer. This is known as the bootstrap loader.
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Differences between desktop, laptop, tablet, smartphone
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Desktops run from mains electricity, tablets, laptops and smartphones use a battery.
Desktops are not portable, tablets, laptops and smartphones are. |
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Difference between local storage and cloud storage
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Local storage is storage on a hard drive or other backing storage device. Cloud storage is storage available online through a provider. The advantage of cloud storage is that it is accessible from anywhere.
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Units of capacity (bits, bytes, KB, MB, GB)
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Bit = 0 or 1Byte = 8 bitsKilobyte = 1024 BytesMegabyte = 1024 KilobytesGigabyte = 1024 MegabytesTerabyte = 1024 GigabytesPetabyte = 1024 Terabytes
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Magnetic storage devices
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Magnetic storage devices use magnetic surfaces to store data. Floppy disks, hard drives and magnetic tapes are magnetic storage devices.
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Optical storage devices
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Optical storage uses light to read and write data. CDs and DVDs use optical storage. Optical storage writes data using a laser. The laser bounces off the surface of the disc and the strength of the reflection reads as a 1 or 0. Writing data works in the same way, but a stronger laser changes the surface of the disc.
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Solid state devices
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A solid state device is a storage device that has no moving parts, and stores data electronically using a memory chip. All USB flash drives and SD cards are solid state. Many new computers use solid state instead of magnetic hard drives.
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Peer to peer network
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A peer to peer network is a network of computers that are not controlled by a central server. Each computer can access other computers on the network, and may share its own files. There is no central server to provide access control or file storage.
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Client/server network
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A client/server network is a network of computers where one computer acts as the main store for files, and provides services like email storage, web access and authentication (usernames and passwords) to other computers.
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Difference between peer to peer and client/server
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A peer to peer network does not have a central storage area. In peer-to-peer, user accounts cannot be controlled by a single server, which means access is not controlled to files or applications.
Client/server networks have a central storage area and control over what users can access files and applications. |
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Optical connections
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Network connects can use an optical connection. Optical cables are made of glass or plastic. Light signals are sent down the cable. Optical cables don't suffer from electrical interference.
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Wireless connections
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Wireless connections can be made using Wifi, Bluetooth or cellular signals like 3G and 4G data signals.
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Wired connections
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Wired connections can be made using coaxial cable (metal cable shielded by a metal outside to protect from interference) or twisted pair cable (pairs of wires twisted together to protect against interference)
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Spyware
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Spyware is software that is designed to monitor a user's actions. Spyware collects internet browsing habits and personal information which may be passed on illegally to third parties.
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Phishing
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Phishing uses emails or websites that look similar to popular websites. If a user is fooled into typing their login details into the web site, the phisher will get hold of their details.
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Keylogging
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Keyloggers are programs that log the keypresses a user makes. This can be used to steal personal data such as passwords or credit card details.
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DOS attack
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A Denial of Service attack involves a large number of connections being made to a single computer on a network. This overwhelms the computer, causing it to stop responding to requests.
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Anti-virus
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Anti-virus software is designed to detect and remove viruses from a computer.
It can do this by scanning every file on a computer, or monitoring the creation of new files and changes to existing files. |
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Encryption
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Encryption means encoding a message so that it cannot be read by anyone but the user that it is indended.
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Biometrics
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Biometric data is data about physical traits, such as retina scans, fingerprint scans or voice signature.
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Firewalls
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A firewall is software or hardware designed to block connections to a computer. The firewall prevents unwanted connections that may be trying to access a computer system without permission.
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HTTPS
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HTTPS is a secure connection for web traffic. All traffic sent by HTTPS is encrypted.
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Security suites
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A security suite is a collection of software tools designed to make a computer more secure. This can include anti-virus, anti-smap and anti-spyware software, as well as a firewall.
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Computer Misuse Act
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The Computer Misuse Act makes it illegal to hack a computer or create a virus.
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Data Protection Act
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The Data Protection Act gives rights to people with data help on computers, and responsibilities to companies that hold data about people. The rights include the right to view and change incorrect data. The responsibilities include keeping data accurate, secure and up to date.
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Copyright, Designs and Patents Act
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The Copyright, Designs and Patents Act makes it illegal to copy software or send it over a network, without the permission of the copyright holder.
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Health and Safety regulation
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Health and safety regulations make sure that employees must:
Provide adjustable chairs, keyboards and screens Provide wrist wrests Provide glare-free lighting, adequate light and glare-free windows. Allow for work breaks and screen breaks. |
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Communication Act
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The Communication Act prevents unauthorised access to networks, such as using another person's Wifi signal without permission.
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Carbon footprint
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Carbon footprint is the volume of carbon dioxide created by a particular process. This indicates how much polution is created, and how much energy is used.
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Energy use
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Energy use can be minimised by turning computers off and using low power processors and monitors.
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Disposal of IT equipment
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IT equipment must be properly disposed. Recycling IT equipment makes sure that harmful chemicals are dealt with and valuable parts are re-used.
IT equipment that stores data should be destroyed so that data cannot be retrieved after use. |
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Colour depth
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Colour depth is the number of bits used for each pixel in an image. The more bits that are used, the more colours can be represented - e.g. 8 bits can represent 256 colours (0 to 255) and 4 bits can represent 16 colours (0 to 15)
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Presence check
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A field validation where the field is checked to make sure it is not empty
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Restricted choice
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A field validation that checks that a field has one of a selection of values (usually presented in a menu)
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Field length
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A field validation that checks the length of a field is within a particular range
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Range check
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A field validation that checks that a number is in a particular range (e.g. 1 to 10)
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Concatenation
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"In programming, concatentation is used to join two strings together, for example:
SET string_one TO ""hoo""SET string_two TO ""ha""SET new_string TO string_one & string_two new_string would contain ""hooha""" |
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Array
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A list of data indexed by a number
e.g.SET names TO [Steve, Bill, Brad]SEND names[2] TO DISPLAY This would display Bill |
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ALU
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Arithmetic and Logic Unit. Part of the processor that carries out calculations and logical operations.
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Logical operators
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AND, OR, NOTUsed in conditions (e.g. score>2 OR score<0)
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Relational operators
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Used to compare items in a program, e.g.
IF total > 40 Relational operators include <,>,=,<=,>= and <> (not equal) |
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ASCII
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American Standard Code for Information Interchange. The standard used to represent characters as binary numbers. Every computer uses ASCII to make sure that a file sent from one computer to another will make sense.
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HTML
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Hypertext Markup Language. The language web pages are written in.
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Backing storage
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Devices that store files permanently
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clock speed
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Processor speed, measure in Hertz, the number of instructions per second.
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Cloud storage
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Storage for files that is held online
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Control unit
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Part of the processor that controls the flow of data between the processor and memory
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Registers
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Temporary storage for single items of data in the processor. Used to store parts of calculations.
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Data controller |
Person in a company responsible for all data security (under Data Protection Act)
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Data subject
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Person who has data stored about them (under Data Protection Act)
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Data user
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Employee of a company that uses another person's data (under Data Protection Act)
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Floating point representation
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numbers stored by storing the detail (mantissa) and exponent (range).
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Resolution
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The number of pixels in a bitmap image
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Hacking
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Unauthorised access to a website
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GUI
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Graphical User Interface
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HLL
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High level language. Program code.
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Inkjet printer
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Cheap printers with expensive ink cartridges that print by spraying ink onto a page
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Laser printer
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Expensive printers with cost-effective toner cartidges that use a laser to fix toner powder to a page
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Javascript
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A programming language used for scripting web pages (adding interactity to a HTML document)
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LAN
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Local Area Network
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WAN
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Wide Area Network
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MP3
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File format for storing compressed audio files. Reduces size of file by removing high and low pitched noises.
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NIC
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Network Interface Card
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PNG |
Portable Network Graphics file. A bitmap file type (also a standard file format)
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GIF
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Standard file format for storing bitmaps. Can also store animations.
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AVI
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Standard file format for storing movie files.
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MP4
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Standard file format for storing movies.
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PDF
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Standard file format for storing printable documents.
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Standard File Format
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A file format that can be opened in a variety of applications. This includes JPG, HTML, RTF, text files, PNG, MP3, MP4 and PDF
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WWW
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World Wide Web
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Trojan
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A file that contains a virus, but seems like a normal, working file to the user.
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Worm
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A program that can replicate across a network without a user's help
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Virus
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A program designed to carry out malicious actions on a computer.
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Machine code
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The data that runs directly on the processor. Represented by 0s and 1s
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Resolution independence
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A graphic that can be scaled to any size without pixellating (it must be stored as a vector)
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Tags
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elements of an HTML document used to control the formatting of the page
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Transmission media |
A way of sending data from one point to another (e.g. cables)
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Translator
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A program that turns HLL into machine code |
