Tamil Nadu HSE Second Year Computer Applications flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

2's complement

A method of representing negative binary numbers: invert every bit of the number (1's complement) and add 1. It lets subtraction be done as addition and gives a single representation of zero.

Hexadecimal conversion

Hexadecimal uses base 16 with digits 0-9 and A-F. Each hex digit equals exactly four binary bits, so binary is converted by grouping bits in fours from the right.

Unicode

A character encoding standard that assigns a unique code point to characters of almost every writing system, unlike 7-bit ASCII which covers only 128 characters.

Cache memory

A small, very fast memory placed between the CPU and main memory that holds recently used instructions and data to reduce average access time.

Control unit

The CPU component that fetches each instruction from memory, decodes it, and generates the control signals that direct the ALU, registers and I/O units.

Compiler versus interpreter

A compiler translates the entire source program into machine code before execution, while an interpreter translates and executes one statement at a time, stopping at the first error.

Mail merge

A word-processing feature that combines one main document with a data source of records to produce a separate personalised copy for each record, such as letters or labels.

Header and footer

Areas at the top and bottom margins of a document that repeat on every page. They commonly hold page numbers, document titles, dates or organisation names.

Absolute cell reference

A reference written with dollar signs such as $A$1 that stays fixed when a formula is copied to another cell, unlike a relative reference which shifts.

Slide transition

The visual effect applied to the change from one slide to the next during a slide show, distinct from animation, which applies to objects within a single slide.

Flowchart symbols

Oval for start and end, parallelogram for input and output, rectangle for a process, diamond for a decision, and arrows for the direction of flow between steps.

Modulus operator

The % operator returns the remainder of an integer division, for example 17 % 5 gives 2. It is often used to test divisibility or extract digits.

do-while loop

A loop that executes its body first and tests the condition afterwards, so the body always runs at least once even if the condition is false initially.

Call by reference

A parameter-passing method in which the function receives the address of the original variable, so changes made inside the function affect the caller's variable.

Array index range

In C++ and Python, an array or list of n elements is indexed from 0 to n-1. Accessing index n or beyond is an out-of-bounds error.

Primary key

A column or set of columns whose value uniquely identifies each row of a table. It cannot contain duplicate values or NULL.

Foreign key

A column in one table whose values must match a primary key value in another table, enforcing referential integrity between related tables.

HAVING clause

A clause that filters groups after GROUP BY has been applied, typically using aggregate functions, whereas WHERE filters individual rows before grouping.

Star topology

A network layout in which every device connects to a central hub or switch. A single cable failure affects only that device, but hub failure stops the network.

DNS

The Domain Name System translates human-readable domain names such as example.com into numeric IP addresses that computers use to route requests.

TCP versus UDP

TCP is connection-oriented, acknowledges packets and retransmits lost ones, so it is reliable. UDP is connectionless with no guarantee, used for streaming and gaming.

IPv4 address

A 32-bit logical address written as four decimal octets separated by dots, each from 0 to 255, for example 192.168.1.1. IPv6 uses 128 bits instead.

CSS box model

The structure of every HTML element as nested boxes: content, then padding, then border, then margin. Width and height normally apply to the content box.

Class versus id selector

A class selector (.name) may be applied to many elements, while an id selector (#name) must be unique within one HTML page and has higher specificity.

HTML form input types

The input element's type attribute chooses the control: text, password, radio, checkbox, email, number, date, file or submit. The name attribute is the key submitted.

Empty HTML tags

Tags with no closing tag or content, such as <br> for a line break, <hr> for a horizontal rule, and <img> for an image. They are also called void elements.

SaaS

Software as a Service is a cloud model in which the provider hosts and maintains the application, and users access it through a browser, usually by subscription.

IoT perception layer

The lowest Internet of Things layer, containing physical devices, sensors that collect data and actuators that act on the environment. Network and application layers sit above it.

B2C e-commerce

Business to Consumer e-commerce, in which a company sells products or services directly to individual customers online, as in most retail shopping websites.

Phishing

A fraudulent email, message or website that imitates a trusted source to trick a user into revealing passwords, card numbers or one-time passwords.

Ransomware

Malicious software that encrypts a victim's files and demands payment for the decryption key. Regular offline backups are the main defence against data loss.

Two-factor authentication

A login method requiring two different proofs of identity, such as a password plus a one-time code, so a stolen password alone is not enough to gain access.