O-Level Computing 7155 Key Terms & Vocabulary

Comprehensive vocabulary flashcards generated from the O-Level Computing 7155 revision notes.

Computer

A device that receives and processes data according to a set of instructions and produces the processed data.

Computer architecture

A description of how a computer is designed and built to function, including how its various parts are designed, organised and connected.

Bit

A binary digit that takes on a value of either $0$ or $1$.

Byte

A binary number made up of eight bits.

Processor (CPU)

The part of the computer that processes data and follows instructions.

Main memory

A device that is used to store data and instructions temporarily for immediate use by the processor.

Secondary storage

A way of storing large amounts of data that will not be lost when the power supply is interrupted.

Volatile

Lost when the power supply is interrupted.

Address

A number that is used to locate a byte in memory.

Data bus

A bus that is used to transport data between memory and the processor. Bi-directional: able to work in two directions, to and fro.

Address bus

A bus that is used to specify memory address information. Uni-directional: able to work in one direction only (processor $\rightarrow$ memory).

Motherboard

The main circuit board in a computer that connects all the components together.

Denary (decimal)

A number system that is made up of $10$ unique digits ($0\text{--}9$). Base-10: place values $10^N$.

Binary

A number system that is made up of two unique digits ($0$ and $1$). Base-2: place values $2^N$.

Hexadecimal

A number system that is made up of $16$ unique digits ($0\text{--}9$ and $\text{A--F}$). Base-16: place values $16^N$.

Two's complement

System used by computers to represent both positive and negative numbers. The two's complement of a number is $2^N$ minus the number ($N = \text{number of bits}$).

Integer overflow

Result when an operation produces an integer that exceeds the limits of the representable range.

Character encoding

The assignment of numbers to characters.

Boolean

A data type representing either True or False.

Truth table

A table that shows the resulting output for every possible combination of inputs.

Logic gate

An electrical circuit that performs logical operations based on one or more inputs and produces a single output.

Logic circuit diagram

A visual representation using symbols to show how the component logic gates are connected together in a logic circuit.

Sum-of-Product (SOP)

A Boolean statement where the AND terms are ORed together.

Sequence

A construct for performing multiple instructions in a fixed order.

Selection

A construct for choosing between two or more branches based on a particular condition (if / elif / else).

Iteration

A construct for repeating instructions while a particular condition is true (while / for).

Parameter

Special variable in a user-defined function that an argument is assigned to when the function is called.

Argument

An additional value supplied as input to a function call.

Local variable

A variable that is created inside a user-defined function and can only be used in the function's body.

Global variable

A variable that is created outside of a user-defined function and is readable from the function's body if its name is not hidden by a local variable.

Data validation

Checking input data before it is processed to ensure that it is sensible, complete and within acceptable boundaries.

Syntax error

Errors caused by incorrect source code that violate the rules of the language.

Logic error

Errors that cause the program to not behave as expected.

Run-time error

Errors that occur while a program is running.

Test case

A set of inputs and the corresponding set of expected outputs for a particular program which is used to verify whether the program works as intended.

Trace table

A tabulation of changes in the variables and output of an algorithm when performing a dry run.

Computational thinking

A process of formulating problems so their solutions can be represented as algorithms.

Decomposition

Breaking down a complex problem or process into smaller and more manageable parts.

Generalisation

Identifying common features from two or more similar items.

Waterfall model

The traditional model where progress flows through the stages in a sequential manner and each stage is completed before moving on to the next.

Local area network (LAN)

A network of computing devices connected within a small geographical area, typically within the same building, such as a home, school or office.

Wide area network (WAN)

A network of computing devices covering a large-scale geographical area, typically across multiple geographical locations.

Network protocol

A set of standards and rules that govern how two or more devices communicate over a network.

Security

The practice of protecting the confidentiality, integrity and availability of data.

Privacy

The practice of protecting the confidentiality and control of personal data.

Adware

A type of malware that installs itself without the user's knowledge and displays unwanted advertisements.

Spyware

A type of hidden malware that secretly collects personal information about its users and transmits this information to attackers without the users' knowledge.

Phishing

The use of emails, messages and fake websites that appear to be from reputable companies to steal personal data from users.

Pharming

The interception of requests sent from a computer to a legitimate website and the redirection of those requests to a fake website to steal personal data.

Intellectual property (IP)

Creations of the mind that have value but can exist purely as data with no physical form.

Software piracy

The crime of copying, distributing and/or using copyrighted software in a manner that is not permitted by its licence.

Engagement rate

A measure of how much other users actively interact with a social media post.

Artificial intelligence (AI)

The ability of a computer to perform complex tasks without constant human guidance and improve its performance as more data is collected.

Machine learning (ML)

A technique used in AI that enables a computer to perform complex tasks without explicit programming.

Nearest neighbour (NN) method

A simple machine learning algorithm for classification that assigns to a data point the label of its closest neighbouring data point in the training data.

Deepfake

A convincing AI-generated depiction of people doing things they never actually did.

Hallucination

Falsehoods that are presented as facts by generative AI.