Computer Science Concepts and Fundamentals

Vocabulary flashcards covering early computing history, logic gates, computer arithmetic, CPU architecture, memory systems, programming concepts, and operating systems.

Abacus

The earliest computing device, invented around 2500 BC, functioning as a hand-operated calculator for addition and subtraction.

Step-Reckoner

The first automated computing machine that could perform all four basic arithmetic operations (addition, subtraction, multiplication, and division).

Analytical Engine

A general-purpose mechanical computer designed by Charles Babbage that featured memory and a printer, though it was never constructed during his lifetime.

Harvard Mark I

A mechanical relay computer completed in 1944 that executed operations for the Manhattan Project and served as the first programmable computer.

Thermionic Valve

The first vacuum tube, created by John Ambrose Fleming in 1904, containing two electrodes housed within a sealed glass bulb.

Diode

An electronic component that prevents the one-way flow of current, allowing electricity to pass in only one direction.

Colossus Mark 1

An electronic computer built in 1943 using 1,600 vacuum tubes to decrypt Nazi communications, recognized as the first electronic programmable computer.

ENIAC

Completed in 1946, the first general-purpose programmable electronic computer, which remained operational for ten years.

Transistor

An electrically charged semiconductor switch with three wires that relies on quantum mechanics to switch states millions of times per second.

NOT Gate

A logic gate with 1 input and 1 output that outputs true when the input is false, and false when the input is true.

AND Gate

A logic gate with 2 or more inputs and 1 output that produces a true output only if all inputs are true.

OR Gate

A logic gate with 2 or more inputs and 1 output that produces a true output if at least one input is true.

XOR Gate

A logic gate with 2 or more inputs and 1 output that produces a true output only when the inputs are different from each other.

Bit

A single binary digit, representing either a $0$ or a $1$.

Byte

A sequence of 8 bits capable of representing values from $0$ to $255$ in base-two notation.

ASCII

American Standard Code for Information Interchange; a 7-bit character encoding system capable of representing up to 128 distinct characters, including letters, numbers, and symbols.

Unicode

A universal character encoding scheme devised in 1992, most commonly using 16 bits to encode up to 1 million different character codes.

Half Adder

A basic addition circuit that accepts 2 single-bit inputs ($A$ and $B$) and produces two single-bit outputs: a Sum and a Carry.

Full Adder

An arithmetic circuit that accepts 3 single-bit inputs ($A$, $B$, and an incoming Carry) and produces a Sum and an outgoing Carry output.

8-Bit Ripple Carry Adder

A circuit composed of a chain of adders connected sequentially to pass carry bits from one stage to the next when adding two 8-bit binary numbers.

Overflow

An error that occurs when an arithmetic sum produces a carry into a bit position beyond the allocated bit capacity of the circuit.

Carry-Look-Ahead Adder

An advanced adder circuit used in modern processors to calculate carry bits faster and avoid propagation delays.

Arithmetic Logic Unit (ALU)

The component of a CPU that performs arithmetic operations and logical tests.

Gated Latch

A storage circuit that uses logic gates and feedback loops alongside a Write Enable input to store a single bit of information.

Register

A group of gated latches operating together to store a single multi-bit binary value.

Multiplexer

A circuit component that selects a specific row or column address in a memory matrix based on an address input.

Random Access Memory (RAM)

Memory technology that allows any memory location to be read from or written to in any order at any time.

Microarchitecture

A high-level architectural view of computer circuitry that highlights functional blocks rather than individual wiring.

Instruction Register

A CPU register that temporarily holds the current instruction pattern retrieved from RAM so the control unit can decode it.

Opcode

The operation code portion of an instruction bit sequence that specifies the exact command the CPU must execute.

Clock Speed

The frequency at which a CPU carries out steps of the instruction cycle, measured in Hertz ($\text{Hz}$).

Speculative Execution

An optimization technique where advanced CPUs predict the branch direction of conditional jumps to keep the instruction pipeline filled.

Pipeline Flush

The process of clearing incorrect instructions from the CPU processing pipeline when a speculative execution prediction is wrong.

Von Neumann Architecture

A computer design model that unifies program instructions and data within the same shared memory space.

Assembler

A program that converts text-based assembly language instructions into native machine code binary.

Compiler

A specialized program that translates high-level program source code into lower-level machine code that a CPU can directly execute.

Syntax

The set of formal rules governing the structure and composition of statements in a programming language.

Control Flow Statements

Programming constructs, such as IF statements and loops, that dictate the execution order of statements in a program.

Function

A named, reusable block of organized code designed to perform a specific task when called.

Algorithm

A step-by-step set of instructions or rules used to perform a calculation or solve a problem.

Selection Sort

A sorting algorithm with time complexity $O(n^2)$ that repeatedly scans an array for the minimum element and swaps it into position.

Merge Sort

A divide-and-conquer sorting algorithm that splits an array into smaller sub-lists until they are of size 1, then merges them back together in sorted order.

Dijkstra's Algorithm

A graph search algorithm with time complexity $O(n \text{ log } n + I)$ that finds the lowest-cost path between nodes in a weighted graph.

Null Character

A special binary value of $0$ stored in memory to mark the termination point of a character string.

Pointer

A special variable in computer memory that stores the address of another memory location or node.

Integrated Circuit (IC)

A microchip that combines thousands to billions of transistors, resistors, and capacitors onto a single semiconductor wafer.

Moore's Law

An observation made by Gordon Moore in 1965 predicting that the number of transistors on a microchip doubles roughly every two years.

Multitasking

The capability of an operating system to run multiple programs concurrently by giving each program its own memory allocation.

Virtual Memory

An operating system memory management technique that abstracts physical memory addresses, allowing programs to assume their memory starts at address 0.

Kernel

The core component of an operating system responsible for hardware interactions, memory allocation, and process management.

Tape Drive

A magnetic storage device that reads and writes binary 1s and 0s by setting magnetic polarity on a moving strip of tape.