WBCHSE HS Modern Computer Application key terms

The main chip that fetches instructions from memory, decodes them and carries out the arithmetic, logical and control operations a program requires. It coordinates every other component of the computer system.

The part of the processor where arithmetic such as addition and subtraction, and logical comparisons such as AND, OR and NOT, are actually performed. It works on values held in registers and sets status flags after each operation.

A very small, very fast storage location built inside the processor, holding data, addresses or instructions that the CPU is working on at that instant. Registers are far quicker than cache or main memory.

A small, high-speed memory placed between the processor and main memory that keeps recently or frequently used instructions and data. It reduces the average time the CPU waits for information from slower RAM.

A set of parallel conducting lines that carries data, memory addresses and control signals between the processor, memory and input/output devices. Its width and speed strongly influence overall system performance.

A positional number system that uses only the digits 0 and 1, each place value being a power of two. Computers use it because two-state electronic circuits can represent the two digits reliably.

A method of representing signed integers in binary in which the negative of a number is formed by inverting all its bits and adding one. It lets a single adder circuit perform both addition and subtraction.

A branch of algebra dealing with variables that take only the values 0 and 1, combined using AND, OR and NOT. It supplies the rules used to simplify expressions and design digital circuits.

A table that lists every possible combination of input values for a logical expression or circuit and shows the resulting output for each combination. It is used to verify and simplify Boolean expressions.

A basic electronic circuit that performs a single logical operation such as AND, OR, NOT, NAND or NOR on one or more binary inputs and produces one binary output. Gates are combined to build larger circuits.

System software that manages hardware resources such as processor time, memory and disk storage, and provides services that application programs and users rely on. Examples include Windows, Linux and Android.

A translator program that reads a complete source program written in a high-level language and converts it into machine code or an intermediate object file before the program is run.

A translator that reads a source program one statement at a time, converts it and immediately executes it, stopping at the first error it finds. It is slower than a compiler but easier to debug.

The core part of an operating system that stays in main memory and handles the most fundamental tasks: process scheduling, memory management, device control and system calls. Programs reach hardware only through it.

A technique in which part of secondary storage is used as an extension of main memory, so programs larger than physical RAM can run. Unused pages are moved to disk and brought back when needed.

A named storage location in a C program whose value can change while the program runs. Every variable has a data type that fixes how much memory it occupies and what operations are allowed on it.

A specification in C of the kind of values a variable may hold, such as int, float, char or double, together with the amount of memory it needs and the operations permitted on it.

The rule that decides which operator in an expression is evaluated first when several appear together, for example multiplication before addition. Parentheses can override the default order.

A collection of a fixed number of elements of the same data type, stored in consecutive memory locations and accessed by an index that starts from zero in C.

A variable in C that stores the memory address of another variable rather than a value. It allows indirect access to data, dynamic memory allocation and efficient passing of arrays to functions.

A technique in which a function calls itself with a smaller or simpler input until a base condition is reached and the calls unwind. It suits problems such as factorial, Fibonacci and tree traversal.

A linear data structure in which insertion and deletion both happen at one end, called the top, following last-in-first-out order. Typical uses are function calls, expression evaluation and reversing data.

A linear data structure in which elements are added at one end, the rear, and removed from the other, the front, following first-in-first-out order. It models waiting lines and printer job scheduling.

A linear data structure made of nodes, each holding a data item and a pointer to the next node. Unlike an array it grows or shrinks at run time and needs no contiguous memory.

A hierarchical data structure in which each node has at most two children, called the left child and the right child. Traversals such as preorder, inorder and postorder visit every node exactly once.

A column, or a minimal set of columns, whose values uniquely identify each row of a table. It cannot be null, and a table may have only one primary key.

A column or set of columns in one table that refers to the primary key of another table, creating a link between the two. It keeps related data consistent by rejecting invalid values.

The process of organizing tables and their columns to reduce redundant data and avoid insertion, deletion and update anomalies. It usually proceeds through normal forms such as 1NF, 2NF and 3NF.

Structured Query Language, the standard language for creating, querying, updating and controlling relational databases. Its statements are grouped into DDL, DML, DCL and transaction-control categories.

Data Definition Language: the group of SQL statements such as CREATE, ALTER and DROP that define and change the structure of database objects like tables, views and indexes.

A set of agreed rules that governs how data is formatted, addressed, transmitted and acknowledged between devices on a network. Without shared protocols, machines from different makers could not communicate.

A numeric label assigned to a device on a network so that data can be routed to it. IPv4 uses 32 bits, written as four decimal numbers separated by dots.

A local area network connects computers and devices within a limited area such as a room, building or campus, usually under one administrative control and offering high data rates.

A network device that receives packets, reads their destination IP addresses and forwards them along the best path towards another network. It joins different networks and is a key device of the Internet.

Domain Name System: a distributed naming service that translates human-friendly domain names such as example.com into the IP addresses that computers use to reach the correct server.

HyperText Markup Language, the language used to describe the structure and content of web pages through elements marked by tags such as headings, paragraphs, lists, links and images.

Uniform Resource Locator: the address that identifies a resource on the web, giving the protocol, the server name and the path of the file, for example http://site.org/page.html.

HyperText Transfer Protocol: the request-response protocol that web browsers and servers use to exchange pages and other resources. It defines methods such as GET and POST and status codes such as 404.

Cascading Style Sheets: a language of rules used to control how HTML content looks, including colours, fonts, spacing and layout, kept separate from the page structure.

Client software that requests web resources from servers, interprets HTML, CSS and scripts, and displays the resulting page. Examples are Chrome, Firefox and Edge.