Computer Science Review: Hardware, Architecture, and Systems

Comprehensive practice flashcards defining core vocabulary across Computer Science topics including number systems, peripherals, storage, data transmission, CPU architecture, system software, and data validation.

Binary Number System

A base-$2$ number system that uses only two characters: $0$ and $1$.

Hexadecimal Number System

A base-$16$ number system that uses $16$ characters ($0$ to $9$ and $A$ to $F$). It provides a shorter way to represent bytes and is easier for programmers to read.

Register

A temporary high-speed storage location inside a computer that holds binary data (e.g., an $8\text{-bit}$ or $16\text{-bit}$ register).

Digital Data

Data that has been converted into binary format ($0$s and $1$s) so that it can be processed by a computer.

Analogue Data

Continuous real-world data used by humans and analogue devices such as actuators.

Microprocessor

An integrated circuit device used to control the operation of a computer or appliance, utilizing registers to execute operations.

Hexadecimal Color Representation

A color notation used in HTML codes where three color components (Red, Green, Blue) are each assigned a two-digit hexadecimal value from $00$ to $FF$.

MAC Address Structure

A Media Access Control address consisting of a $12\text{-digit}$ hexadecimal number ($48\text{ bits}$), divided into the manufacturer ID number and the hardware serial number.

Barcode Scanner

An input device that scans barcodes using reflected light to read encoded data into binary, widely used in supermarkets for pricing and stock control.

QR Code Scanner

An input device or mobile application that uses a camera or sensor to capture light reflected from a 2D matrix barcode and convert it into binary.

Resistive Touch Screen

A touch screen technology composed of flexible layers; when pressed, the upper layer touches the conductive bottom layer, causing a voltage change that registers the touch coordinate.

Capacitive Touch Screen

A touch screen technology that maintains an electrostatic current across the glass surface; contact with a conductive object (such as a bare finger) alters the electrostatic field to locate touch coordinates.

Accelerometer

A sensor containing a piezoelectric cell whose output changes with motion, measuring acceleration, rapid deceleration, or orientation (e.g., switching phone screens between portrait and landscape).

Actuator

An electromechanical output component that converts electrical energy into physical movement to control or operate an external mechanism (such as opening a valve or turning a motor).

DLP Projector

Digital Light Processing projector; an output display device that reflects light using millions of micro-mirrors to project high-definition digital images.

Pixel

Short for picture element; the smallest discrete controllable component of a digital raster image or screen display.

Computer Memory Hierarchy

The structural arrangement of storage in a computer system, showing direct high-speed links between CPU, Cache Memory, Primary Memory, and Secondary Memory.

Kibibyte (KiB)

A binary unit of data measurement equivalent to $1024\text{ bytes}$ ($2^{10}\text{ bytes}$).

Primary Storage

Memory directly accessible by the CPU that stores instructions and data temporarily with high-speed read/write access (e.g., RAM, ROM, cache memory).

Secondary Storage

Non-volatile storage that is not directly accessible by the CPU, providing permanent retention of files, operating systems, and applications (e.g., HDD, SSD).

Magnetic Storage

Secondary storage technology that utilizes spinning platters divided into tracks and sectors, magnetizing microscopic dots using a read-write head to store binary values ($1$ for magnetized, $0$ for unmagnetized).

Optical Storage

Storage media (such as CD, DVD, and Blu-ray) that uses laser beams to read and write data encoded as microscopic pits and lands along spiral or concentric tracks.

Solid-State Storage

Non-volatile storage media containing floating gate and control gate transistors arranged in a grid, retaining binary data electrically without any mechanical moving parts.

Lossy Compression

A data compression technique that reduces file sizes significantly by permanently identifying and removing redundant or imperceptible data (e.g., JPEG, MP3, MP4).

Lossless Compression

A data compression technique that reduces file size without discarding any original data, allowing the exact original file to be reconstructed (e.g., ZIP, PNG, RLE).

Run-Length Encoding (RLE)

A lossless compression algorithm that detects sequences of identical repeating elements (such as adjacent pixels of the same color) and stores them as a frequency count and value pair.

MIDI (Musical Instrument Digital Interface)

A communications standard and file format storing musical performance instructions (note pitch, velocity, duration) rather than digitized audio waveforms.

Data Packet Structure

The formatted unit of network transmission comprised of three sections: Packet Header (destination/sender addresses, sequence number), Payload (actual user data), and Trailer (error-checking bits).

Packet Switching

A network communication method in which data packets travel independently across different routes through intermediate routers and are reordered into the original message at the destination.

Serial Transmission

The transmission of data sent one bit at a time sequentially down a single physical wire or channel.

Parallel Transmission

The transmission of multiple bits (typically one byte) simultaneously along multiple parallel physical channels or wires.

Simplex Transmission

A data transmission mode that allows signal transmission in one fixed direction only (e.g., microphone to computer, or computer to monitor).

Half-Duplex Transmission

A communication mode where data can flow in both directions across a link, but only in one direction at any given time (e.g., walkie-talkies).

Full-Duplex Transmission

A communication mode in which data can be transmitted in both directions simultaneously across a network connection.

Automatic Repeat Request (ARQ)

An error-control protocol that uses acknowledgements and timeouts; if the sender receives no acknowledgement within a specified time limit, the data frame is automatically resent.

Echo Check

An error detection mechanism where the receiving system transmits the received data back to the sending computer, which compares it against the original data to detect transmission discrepancies.

Check Digit

A redundant digit calculated mathematically from the digits in an identification code, appended to the code and verified upon data entry to catch transposition or omission errors.

Von Neumann Architecture

A computer design architecture where instructions and data share the same physical memory and are fetched, decoded, and executed sequentially by a single processor.

Program Counter (PC)

A CPU register that holds the memory address of the next instruction waiting to be fetched and executed, incrementing after each fetch cycle.

Memory Address Register (MAR)

A CPU register that stores the memory address currently being read from or written to via the address bus.

Memory Data Register (MDR)

A CPU register that temporarily holds data fetched from memory or data waiting to be transferred and written into system memory.

Accumulator (ACC)

The primary register of the Arithmetic Logic Unit (ALU) used to hold operands and store the immediate arithmetic and logical results of processing.

Current Instruction Register (CIR)

A CPU register that holds the current instruction while it is being decoded and executed by the Control Unit.

Address Bus

A unidirectional bus that carries memory addresses from the processor to system memory or input/output devices.

Data Bus

A bidirectional communication bus used to transfer actual data and instructions between the processor, memory, and peripherals.

Control Bus

A bidirectional bus that carries control and timing signals from the Control Unit to coordinate activities throughout all computer components.

Embedded System

A dedicated microcomputer system designed to perform dedicated, specialized control functions within a larger mechanical or electrical system (e.g., in washing machines or car braking).

Compiler

A translation program that converts high-level source code into standalone executable machine code all in one go, generating an object program file and an error report.

Interpreter

A translation program that reads, analyzes, and executes high-level source code line-by-line, stopping immediately when an error is encountered.

Software Classification

The hierarchical division of software into System Software (operating systems, utility programs, device drivers) and Application Software (spreadsheets, word processors, databases, browsers).

Interrupt

A signal generated by hardware or software alerting the CPU to temporarily halt its current task and prioritize execution of an Interrupt Service Routine (ISR).

Structure Diagram (Alarm Application)

A top-down modular design chart that decomposes a complete program into distinct hierarchical subroutines and modules.

Validation

An automated check carried out by a computer system to ensure that entered data is sensible, reasonable, and adheres to predefined boundary rules (e.g., range, type, length).

Verification

A process of checking that data entered into a computer accurately matches the source data, using methods such as double-keying or visual checks.