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179 Cards in this Set
- Front
- Back
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What is data? |
Raw, unorganized facts that are yet to be processed |
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What is information? |
Data that has been processed, organised, structured, or presented in a certain context |
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What is a variable? |
A structure that can hold data and are uniquely named by the programmer |
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What is the feature of a variable? |
The data assigned to it is held until it is changed or the program completes |
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What is a constant? |
A structure that can hold data but their initial assigned value cannot change |
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What is a data type? |
A way of classifying various types of data and what actions they can perform |
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Give examples of data types (5) |
Integer Boolean Real Character String |
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What is an integer? |
A whole number |
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What is a boolean? |
A binary variable that can be 0 or 1 (true or false) |
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What is a real? |
A decimal number |
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What is a character? |
A single unit of information |
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What is a string? |
Multiple characters |
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What is an array? |
An array is an ordered arrangement of data elements that are accessed by referencing their location within the array |
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What is indexing? |
Referencing the location of data in an array |
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What is a one dimensional array? |
Array that stores information in one direction (horizontal) |
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What is a two dimensional array? |
Array that stores information horizontally and vertically |
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What are the three types of boolean? |
AND OR NOT |
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What is a data structure? |
A collection of different data elements which are stored together in a clear, structure form |
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What is a dictionary? |
A structure that stores values alongside different keys |
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How can data structures make code simpler? (3) |
They are stored in a clear, structured form Errors are easier to be identified More efficient |
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What is efficiency? |
How many lines of codes are used |
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What is program flow control? |
The order in which a program is executed |
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Give advantages of structure programs (4) |
Saves time as complexity of task is decreased Code has increased clarity Errors easier to identify Many programmers can work on one program at the same time |
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What are flow charts used for? |
Plan programs and represent structure |
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What does a rounded rectangle represent? (2) |
Start of a process and has only one output End of a process and has only one input |
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What does a rectangle respresent? |
A process carried out and has an input and output |
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What does a diamond represent? |
A question with two answers (boolean choice) and has one input and two outputs |
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What are the basic buildings blocks of coded solutions? (3) |
Selection statements Iteration statements Sequences |
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What is a selection? |
When a program's execution is determined by boolean statements |
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What is an iteration? |
A statements that is executed in a loop until it's criteria are met |
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What is a sequence? |
When each action follows the previous action |
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What are procedures and functions? |
Named blocks of code that can be used and reused to perform specific tasks |
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What is the difference between a procedure and a function? |
Procedures perform a task without returning a value Functions return a value |
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Why are functions useful? |
They increase the code efficiency |
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What is a parameter? |
A variable given as information to a function/procedure |
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What is a return value? |
Information that comes back from the subroutine |
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What is scope? |
Where a variable/constant/function or procedure is accessible in your code |
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What is the level of scope? |
Determines whether the item in question can be accessed by all of the program or just certain parts |
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What are global variables? |
Variables that can be accessed anywhere in the code |
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What are local variables? |
Variables declared within a function or procedure, so can only be accessed within there |
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What are the types of errors (3) |
Syntax Run-time Logic |
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What is a syntax error? |
When a program can't execute because there is a piece of language that can not be understood as it doesn't follow the rules of the language |
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What are run-time errors |
When the program requires the computer to complete an operation it cannot handle |
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What are logic errors? |
When a program executes as normal, but not as the programmer expects |
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What is debugging? |
Testing for errors during the program's execution |
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What are debuggers? |
Tools that help debug a program |
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What are the features of debuggers? (3) |
Watches and displays variables Breakpoints that halt code that a specific point Step allows code to run line by line |
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What are trace tables? |
Tables that list the variables step by step to test for logic errors |
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What is a computer system? |
Hardware and software working together to create a working solution |
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Give examples of computer systems in the modern world (4) |
Allow people around the world to contact and work together Allow people to access data securely from anywhere Can improve quality of life (bionic legs) Can save lives (hospital robots) |
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What is a reliability? |
When a computer system can be depended on to work almost all of the time |
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What is robustness? |
The ability of a computer system to cope with execution errors or abnormalities |
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Why is reliability and robustness important? (2) |
Allows computer system to be used without chance of failure Without reliability or robustness, the program may fail or not be able to be used at the right time |
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What does CPU stand for? |
Central processing unit |
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What is the function of the CPU? |
It processes and undertakes instructions given by applications and inputs |
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What is the function of the motherboard? |
Links the CPU to the memory and other hardware |
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What is the function of the graphics card? |
Contain a processor like the CPU and can be used to process the graphic portion of the processing load |
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What is the function of the hardrive? |
Stores majority of data |
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What is flash memory? |
Quick accessible memory that can be easily rewritten (eg. flash drive) |
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What does ROM stand for? |
Read only memory |
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What does RAM stand for? |
Random access memory |
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What form of memory is volatile? |
RAM |
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What form of memory is non-volatile? |
ROM |
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What does ROM contain? |
Pre-installed data that cannot be changed |
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What happens in the RAM when a program is opened? (3) |
Program data gets loaded from hard-drive to RAM Reading is quicker from RAM Making the program's use quicker |
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What is happening to hardware as time goes on? (2) |
It is getting smaller So can be used inside phones, tablets and gaming consoles |
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What are the categories of hardware and software (4) |
Input Output Processing Storage |
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What is an input device? |
Hardware that takes an input |
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What is a processing device? |
Hardware or software that processes information |
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What is the purpose of the CPU? |
Process data using the processor in it |
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How is the CPU linked with the processor? |
Everything is linked to the processor through the motherboard The RAM and the cache are linked to the processor through a 'bus' |
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What is the 'bus' |
Communication system that transfers data |
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What is the clock speed/rate? |
The speed at which a microprocessor executes instructions |
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What is the advantage and disadvantage of higher clock speed |
+A process will be completed quicker -More heat produced and power consumed |
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What is the microprocessor? |
A device that fits on one chip |
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What is a multi-core processor? |
Multiple CPUs on a single chip |
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Give an advantage and disadvantage of using a multi-core processor |
+Can run multiple instructions at any given time (one per core) - multitasking -The software must be specifically written to cater for multiple cores so an increase in cores may not affect some applications |
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What is cache storage? |
Stores recently used data so that is can be quickly accessed at a later time |
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What are processor caches? |
Small data stores which contain regularly used instructions that can be quickly accessed by the CPU when required |
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What is a cache hit? (2) |
When a CPU finds stored data in the cache More cache means higher chance of cache hit |
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What is volatile memory? |
Computer memory that only maintains data while it is connected to a power supply |
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Why is volatile memory is used? (2) |
It is faster than other alternatives It is unavailable when powered-down so can protect sensitive information |
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What is non-volatile memory? |
Computer memory that can get back stored data even when not powered |
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What is virtual memory? |
Memory management procedure which is used when all RAM space is used up |
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What is the function of virtual memory? (2) |
Sections of the RAM that have not been recently used are stored temporarily on the hard drive This extends the RAM capacity |
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What is the downside to virtual memory? |
Read/write times are slower than RAM |
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What is secondary storage? |
Non-volatile memory that is used to store large amounts of data permanently |
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Give forms of secondary storage with an example for each (3)
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Flash memory - USB stick Optical media - CDs Magnetic media - Hard disk drive |
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What is optical media? (3) |
Binary data is stored as variations of being on the surface When light is shined from an optical drive, it hits a pit and reflects differently to when it hits a land (flat spot) This allows the drive to detect differences and read data |
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What is magnetic media? (3 points) |
Storage devices that use moving read and write heads that contain electromagnets. On the surface of the storage medium, there are magnetized dots that can be magnetically forced to face in one of two directions This represents 1 (on) or 0 (off) depending on the direction they are facing |
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What is a solid state drive? (3 points) |
Form of flash memory that is non-mechanical They contain transistors that can be in state of on or off This state is retained when there is no power |
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What are algorithms? |
Computational solutions to problems that always finish and return an answer |
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What is binary code? |
Code that consists of two digits: 0 or 1 (on or off) |
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What do computers use binary for? |
ALL data and instructions |
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What is a bit? |
Short of binary digit (0 or 1) |
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What is a nibble?
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Four bits |
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What is a byte? |
Eight bits or two nibbles |
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What is a kilobyte? |
1024 bytes |
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What is a megabyte? |
1024 kilobytes |
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What is a gigabyte? |
1024 megabytes |
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What is a terabyte? |
1024 gigabytes |
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What are the types of data that binary can represent? (5) |
Text Sound Image Integer Date |
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How is sound represent in binary? (3 points) |
Data must be converted from analogue to digital data (eg. using a microphone) An analogue sound wave is divided up into lots of individual samples Each sample can then be stored in binary code (usually 16 or 32 bits per wave) |
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What is a bitmap image? |
A digital image composed of individual pixels |
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How are bitmap images represented in binary? (3 points) |
All bitmaps are stored as an array of these pixels A monochrome bitmap will store 1 for a black pixel, and 0 for a white pixel Pixels in a colour bitmap are matched to a colour palette, with each shade consisting of 1s and 0s |
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How are characters represented in binary? |
Each of the 128 characters is associated with a 7-bit-binary number so a computer can understand the characters |
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What are the limitations of ASCII? (2) |
Limited to 128 characters Only applicable to the country it comes from |
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What base is binary? (2) |
Base-2 0 and 1 |
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What base is Hexadecimal? (2) |
Base-16 0 - 9 and then A - F |
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What base is denary? (2) |
Base-10 0 - 9 |
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What is the software development life cycle? |
The steps that new software must go through |
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What are the steps of the cyclical cycle? (5) |
Requirement analysis Design Implementation Testing Evolution |
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What happens at the requirement analysis stage? |
Programmers, designers and clients discuss the needs of the user so it is clear what is required |
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What happens at the design stage? |
The solution is planned using the specifications discussed in the first stage |
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What happens at the implementation stage? |
Sections in the design are turned into code |
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What happens at the testing stage? |
The program is tested against the specification, to ensure the code written really provides a solution of the problem |
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What happens at the evolution stage? |
Changes or upgrades that the software goes through after it is delivered to the client. |
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Give two other types of lifecycle models |
Waterfall model Spiral model |
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Give two advantages and two disadvantages of a cyclical life cycle model |
+Clearly defined +Simple -Difficult to measure progress -No software developed till later on |
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Give two advantages and two disadvantages of a cyclical waterfall model |
+Simple and good for small projects +Easy to manage -Cannot be used if specification could change -No software developed till later on |
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Give two advantages and disadvantages of a spiral model |
+Good for larger solutions with many sections+Software is developed early -Almost never ending, so costs are high -Hard to manage |
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What is a prototype? |
An early model of a product built to show how the final product will work |
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What are the advantages of developing a prototype? (3) |
+Offers early indication of whether or not the solution developed will meet the specification +Offers the client a way to revise the specification if they realise something else is needed |
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What are the disadvantages of developing a prototype? (3) |
-Too much time spent creating prototype -Prototype may be adapted to create the final solution which may be poor quality |
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What is application testing? |
Using the application in controlled conditions to see how it works |
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Why is rigorous testing required? (2) |
Determines whether the developers have met the specifications Ensures that the end user's experience is not affected by bugs and errors |
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What are the four types of testing? |
Functional
Beta Stress Modular |
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What is functional testing? |
Testing in normal conditions to ensure that the software is in line with the specification |
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What is beta testing? |
Testing done by a sample of END USERS under more extreme conditions |
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What is stress testing? |
Data is entered into the program outside the specification limits to test robustness |
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What is unit/modular testing? |
Code is split up into individual sections which are then tested separately |
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What is the advantage of unit testing? |
Errors can be found very quickly as they can only occur in the small testing |
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What is a test plan? |
Documents created before the testing phase to show what tests will be conducted |
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What is a computer network? |
Two or more computers connected through a communication medium |
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What is a communication medium? |
Physical connection between network (eg. cable) |
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What is the purpose of a network? |
To send and receive data and use the resources of other computers |
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What is a server? |
Computer that provides the services to the clients |
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What is the client? |
Computers that use the service that the servers provide
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What is the user? |
Any person that uses a client to access resources on the network |
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What is protocol? |
Written rules used for the network communications (eg. IP - internet protocol) |
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What are the advantages of using a network? (3) |
+Sharing resources saves money +Security improved as files are stored on different clients +Data easy to back up on server |
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What are the disadvantages of using a network? (3) |
-Expensive commutations media -Managing large network is complicated -Hackers and viruses can infiltrate network easier than client |
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What is a topology? |
A network layout |
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What is bus network? (2) |
All of the clients, servers and resources are connected to one cable (the bus) Messages are sent to all computers, but only the recipient processes and reads it |
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What are the advantages and disadvantages of bus topology? (2) |
+Cheap -More workstations means less performance |
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What is ring topology (2) |
Each device is connected to two other devices Message travels to the next device until it reaches the recipient |
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What are the advantages and disadvantages of ring topology? (2) |
+Quicker - flowing in one direction - no data collisions -If any cable fails, whole network fails |
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What is star topology? |
Workstations are connected seperately to a central hub, switch or router |
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What are the advantages and disadvantages of star topology? (2) |
+Reliable, if one cable fails, other devices will be unaffected -Expensive as it requires lots of cable |
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What is a client server model? |
Structure that splits tasks between servers and clients |
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Give the features of a server (3) |
Wait for requests from clients Serve client requests by sending requested data to clients May communicate with other servers to fulfill requests |
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Give the features of a client (3) |
Waits for replies Receives replies Connects to a small number of servers |
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What is handshaking? |
An automated process of negotiation that needs to occur to establish a connection with a foreign device Negotiates what protocol parameters to use |
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Give examples of protocol parameters (3) |
Speed of transmission Error-testing methods Size of bytes |
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What is important to know when coding for a client server model? (3) |
Data should be stored on a server Protocols need to be considered Harder than client programming |
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Give the features of server side scripting (3) |
Display the page which the client renders viewable Process client inputs Use permanent storage such as database |
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Give examples of programs that can script server side (3) |
PHP, Python, Java |
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Give the features of client side scripting (4) |
Contacts with server Code must make interactive webpages using source code from server Interacts with local storage Done in HTML, CSS and sometimes Javascript |
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What is external code? |
Websites that share some of their code so that other programmers can integrate it into their code |
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Give an example of external code |
Twitter allows you to use use features of twitter on their website |
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Give the advantages and disadvantages of external code (2 each) |
+Saves time and money +Benefits the provider -Programmers may find it hard to embed the code -Code can't be changed easily |
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What is a table? |
A two dimensional representation of data that is stored in rows and columns |
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What are relational databases? |
Databases that consist of more than one table linked using key fields |
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What is a primary key? |
An attribute or collection of attributes whose values uniquely identify each row in a relational database |
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What is a foreign key? |
An attribute or collection of attributes whose values are intended to match the primary key of a different table |
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What are records? (2) |
Complete set of information Comprised of fields |
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What are fields? |
Single set of data that you get from intersecting a column and a row |
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What is a query? |
Question posed to the database using SQL |
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What is a relationship |
Comparison of data in key fields so data in two tables are linked |
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What is an index? |
Used to help people find certain columns and fields in a database |
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What is a query? |
Question posed to the database using SQL |
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What is SQL? |
Programming language designed to manage data within a relational database |
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What does * stand for in SQL? |
All |
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Give 7 examples of SQL syntax Keywords (3 sections) |
SELECT, FROM, WHERE INSERT INTO, VALUES UPDATE, SET |
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Give SQL syntax to select columns that are not ID of '10' from 'Name' and 'ID' from table 1 (3 SQL Keywords) |
SELECT Name, ID FROM table 1 WHERE ID <> 10 |
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What does NULL mean in SQL? |
No data is in that field |
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Give SQL syntax to add 'Jim' to 'Name' column of table1 (3 SQL Keywords) |
INSERT INTO table 1 (Name) VALUES (Jim) |
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Give SQL syntax to update table 1 column 'ID' with the value '51' where the value is 'Jim' (3 SQL Keywords) |
UPDATE table1 SET ID = 51 WHERE Name = Jim |
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Give examples of computers in society (3) |
Software replacing stock brokers as they can deal with large numbers New technology in medicine keeps people alive and improves quality of people Military improved by software |
