ASSEB HS Computer Science and Application flashcards

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

Von Neumann architecture

A design in which program instructions and data share the same memory and bus. The CPU repeatedly fetches, decodes and executes instructions, so instruction and data transfers cannot happen simultaneously.

Two's complement

A signed binary representation where the leftmost bit has negative weight. Negating a value means inverting all bits and adding one, giving one zero and a range from minus two to the power n minus one.

Pass by value

A parameter-passing mechanism where the called routine receives a copy of the argument. Changes made inside the routine do not affect the caller's original variable, unlike pass by reference.

Binary search

A search on a sorted array that compares the target with the middle element and discards half the remaining range each step, running in logarithmic time but requiring sorted input.

Hash table

A structure mapping keys to values through a hash function. Average lookup, insertion and deletion are constant time, but collisions must be resolved by chaining or open addressing.

TCP versus UDP

TCP is connection-oriented, ordered and reliable with acknowledgements and retransmission. UDP is connectionless with no delivery guarantee, giving lower overhead for streaming and real-time traffic.

ACID properties

Four transaction guarantees: atomicity means all or nothing, consistency preserves valid states, isolation prevents interference between concurrent transactions, and durability keeps committed data after failure.

Waterfall model

A sequential development process moving through requirements, design, implementation, testing and maintenance. Each phase completes before the next, making late requirement changes expensive.

CIA triad

The three core security goals: confidentiality restricts reading to authorised parties, integrity prevents unauthorised alteration, and availability ensures systems and data are accessible when needed.

Short-circuit evaluation

A rule where the second operand of a logical operator is evaluated only when needed. In A AND B, if A is false, B is skipped; in A OR B, if A is true, B is skipped.

Stack data structure

A last-in-first-out collection where insertion and removal happen at one end called the top. Push and pop are constant time; it supports undo, expression evaluation and function calls.

Big-O notation

An upper bound on an algorithm's growth rate as input size increases, ignoring constants and lower-order terms. For example, three n squared plus five n is written as O of n squared.

Subnet mask

A bit pattern that separates the network portion of an IP address from the host portion. A mask of 255.255.255.0, equivalent to a slash 24 prefix, leaves eight host bits.

Primary key

A column or combination of columns that uniquely identifies each row in a table. It cannot be null, and each table may have at most one primary key.

Unit testing

Testing individual components in isolation from the rest of the system, usually automated. Unit tests are fast and pinpoint defects early, but cannot reveal integration problems.

Symmetric encryption

Encryption where sender and receiver share one secret key for both encryption and decryption. It is fast and suits bulk data, but key distribution is the main challenge.

Digital divide

Unequal access to devices, connectivity, skills and affordability across groups and regions. It affects education, employment and participation in civic life, and is addressed by access and training policies.

Lossy compression

A method that permanently discards some data to reduce file size, as in JPEG images and MP3 audio. It achieves smaller files than lossless methods but cannot restore the original exactly.

Full adder

A combinational circuit adding three bits: two operands and a carry-in. It outputs a sum and a carry-out, and can be built from two half adders plus an OR gate.

Deadlock conditions

Four simultaneous conditions cause deadlock: mutual exclusion, hold and wait, no preemption, and circular wait. Breaking any one condition prevents the deadlock from occurring.

Record data structure

A composite type grouping named fields that may have different types, such as a student record with name, age and grade. Fields are accessed by name rather than index.

Topological sort

An ordering of vertices in a directed acyclic graph where every edge points from earlier to later. It sequences dependent tasks and is impossible if the graph contains a cycle.

Packet switching

A technique splitting data into packets that are routed independently and reassembled at the destination. It shares network capacity efficiently but can reorder or drop packets.

Referential integrity

A database constraint requiring every foreign key value to match an existing primary key value, or be null. It prevents orphaned records and keeps relationships consistent.

Boundary value analysis

A black-box test design technique choosing inputs at the edges of valid ranges, such as minimum minus one, minimum, maximum and maximum plus one, because defects cluster there.

Multi-factor authentication

Authentication requiring two or more different factor types, such as a password plus a one-time code. Combining different types is stronger than repeating one type.

Informed consent

Agreement to data collection or participation given after clear explanation of purpose, use, risks and the right to withdraw. It must be voluntary, specific and revocable.

Pipelining

A processor technique overlapping instruction stages so several instructions are in progress at once. It increases throughput but is limited by data, control and structural hazards.

Logical shift

A bit shift that fills vacated positions with zeros. A left shift multiplies an unsigned value by powers of two, while a right shift divides, discarding the remainder.

Syntax versus logic error

A syntax error breaks the language's grammar and is detected before execution. A logic error is valid code producing wrong results, found only by testing and tracing.

Dynamic programming

A technique solving problems with overlapping subproblems and optimal substructure by storing subproblem results, either through memoised recursion or bottom-up tabulation, avoiding repeated work.

TLS handshake

The process establishing a secure session: the client and server agree parameters, the server proves identity with a certificate, keys are exchanged, and encrypted communication begins.