Tamil Nadu HSE Second Year Computer Science flashcards

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

2's complement

A way to represent signed binary numbers: invert all bits of the number and add 1. It lets subtraction be performed as addition and gives one unique zero.

Hexadecimal

A base-16 number system using digits 0-9 and letters A-F. Each hex digit represents exactly four binary bits, making it a compact notation for memory addresses.

Logic gate

A hardware circuit that performs a Boolean operation on one or more binary inputs to produce a single output, such as AND, OR, NOT, NAND, NOR or XOR.

Von Neumann architecture

A computer design in which the CPU, memory and input/output units share a single memory holding both instructions and data, connected by a common bus.

Stack (LIFO)

A linear data structure in which insertion and deletion happen only at one end called the top, so the last element pushed is the first one popped.

Queue (FIFO)

A linear data structure where insertion happens at the rear and deletion at the front, so the first element enqueued is the first one removed.

Postfix expression

An expression in which each operator follows its two operands, for example 2 3 +. It needs no parentheses and is evaluated with an operand stack.

Circular queue

A queue implemented so the rear wraps around to the start of the array after reaching the end, reusing freed slots and avoiding the false-full condition.

Constructor __init__

A special method in a Python class that runs automatically when an object is created, used to initialise the instance attributes of that object.

Inheritance

An object-oriented feature where a child class acquires the attributes and methods of a parent class and can extend or override them, promoting code reuse.

Method overriding

Redefining a parent class method in a child class with the same name and parameters, so the child's version runs when called on a child object.

Encapsulation

Bundling data and the methods that operate on it inside a class and restricting direct outside access, in Python indicated by a double-underscore name prefix.

Primary key

One or more columns chosen to uniquely identify every row of a table. It cannot contain duplicate values or NULL values.

Foreign key

A column in one table that refers to the primary key of another table, enforcing referential integrity so matching parent rows must exist.

HAVING clause

A SQL clause that filters groups after GROUP BY has been applied. Unlike WHERE, it may contain aggregate functions such as COUNT or SUM.

Third normal form

A table is in 3NF when it is in 2NF and no non-key attribute depends transitively on another non-key attribute; each fact is stored once.

OSI model

A seven-layer reference model for network communication: Physical, Data Link, Network, Transport, Session, Presentation and Application, each with defined responsibilities.

TCP versus UDP

TCP is connection-oriented and reliable, using handshakes and retransmission. UDP is connectionless and faster but does not guarantee delivery or ordering.

DNS

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

IP address

A unique numeric label assigned to a device on a network. IPv4 uses 32 bits in dotted decimal form; IPv6 uses 128 bits in hexadecimal.

CSS specificity

The rule deciding which conflicting style wins: inline styles beat id selectors, which beat class selectors, which beat element selectors.

CSS box model

The structure of every HTML element as nested layers: content at the centre, surrounded by padding, then border, then margin on the outside.

JavaScript let and const

Both declare block-scoped variables. A let variable can be reassigned later, while a const variable cannot be reassigned after initialisation.

DOM

The Document Object Model is a tree representation of an HTML page that JavaScript can read and modify to change content, structure and styles.

File open modes

Python mode strings for open(): 'r' reads, 'w' writes and truncates, 'a' appends, 'x' creates new, and adding 'b' opens in binary mode.

try-except-finally

A Python structure where try holds risky code, except handles a raised exception, else runs if none occurred, and finally always runs for cleanup.

List mutability

Lists can be changed after creation: elements can be reassigned, added with append or insert, and removed with remove or pop, all affecting the same object.

String slicing

The expression s[start:stop:step] returns a new substring from start up to but not including stop, with an optional step and negative indices from the end.

Binary search

A search on a sorted array that repeatedly halves the interval by comparing the middle element with the target, giving O(log n) time.

Algorithm

A finite, definite sequence of steps that takes input, performs computations and produces output, terminating after a limited number of operations.

Time complexity

A measure of how an algorithm's running time grows with input size, expressed in big-O notation such as O(n) or O(n log n).

Software piracy

The unauthorised copying, distribution or use of software without a valid licence, an unethical and illegal act that violates the developer's copyright.