OCR GCSE Computer Science - Systems Architecture and Algorithms

Vocabulary practice flashcards covering key concepts in CPU architecture, systems architecture, memory hierarchy, system buses, computational thinking, and algorithm design.

Central Processing Unit (CPU)

The main processor of a computer system that controls all processing, carries out instructions, processes data, fetches data and instructions from main memory, and stores results back into main memory.

Fetch Stage

The initial phase of the CPU instruction cycle where the next instruction and associated data are retrieved from main memory.

Decode Stage

The phase of the CPU instruction cycle where the processor interprets and decodes the fetched instruction.

Execute Stage

The phase of the CPU instruction cycle where the decoded instruction is carried out or performed.

Fetch-Decode-Execute Cycle

The continuous process performed by the CPU to fetch instructions from memory, decode their meaning, and execute the required actions.

Computational Thinking

The process of using computers to solve problems through algorithm development, incorporating abstraction, decomposition, and algorithmic thinking.

Abstraction

The problem-solving technique of representing real-world problems in a computer using variables and symbols while removing or hiding unnecessary details.

Decomposition

The practice of breaking down a complex problem into smaller sub-problems that can be solved, tested, and combined independently.

Algorithmic Thinking

The process of identifying and defining the explicit step-by-step sequence required to solve a problem.

Algorithm

A defined series of sequential steps or rules designed to solve a specific problem or perform an action.

Flowchart

A visual diagram showing inputs, outputs, processes, decisions, and flow of control within an algorithm using standard geometric shapes.

Process Symbol (Flowchart)

A rectangular flowchart shape used to represent an action, calculation, or data modification taking place.

Pseudocode

A flexible, simplified, non-language-specific way of outlining algorithms using short English statements.

Exam Reference Language

A formal, structured, code-like notation used in examinations to represent algorithms clearly without relying on a specific programming language syntax.

Control Unit (CU)

A core CPU component that coordinates operations, monitors hardware, manages input/output, controls internal data flow, and issues control signals like Memory Read and Memory Write.

Arithmetic Logic Unit (ALU)

A CPU component that executes arithmetic operations (addition, subtraction, multiplication, division) and basic logical operations such as AND/OR calculations.

Registers

Small, extremely fast temporary memory locations built directly onto the CPU to hold data and instructions during processing.

Program Counter (PC)

A special-purpose CPU register that holds the memory address of the next instruction to be executed, incrementing after the fetch stage.

Accumulator (ACC)

A special-purpose CPU register that stores the immediate results of arithmetic and logic operations calculated by the ALU.

Memory Address Register (MAR)

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

Memory Data Register (MDR)

A CPU register that temporarily holds the actual data or instruction retrieved from, or about to be transferred to, main memory.

Cache

A small bank of high-speed memory located directly on or near the CPU chip that holds frequently used instructions and data for faster retrieval than RAM.

System Bus

A set of parallel wires connecting computer components together to pass signals, data, and memory addresses between them.

Address Bus

A unidirectional bus that carries memory addresses generated by the processor to main memory or I/O devices.

Data Bus

A bi-directional bus that carries instructions and data between the processor, main memory, and secondary storage.

Control Bus

A bus that transmits control signals (such as Memory Read and Memory Write) from the CPU to indicate operations for connected components.

Random Access Memory (RAM)

Volatile primary main memory located on the motherboard that stores active programs and data currently in use, clearing its contents when powered off.

Read Only Memory (ROM)

Non-volatile primary memory containing permanently etched instructions—such as the Bootstrap Loader—that remain stored when power is lost.

Bootstrap Loader

A program held permanently in ROM that provides the startup instructions required to load the Operating System.

EEPROM

Electronically Erasable Programmable Read Only Memory; non-volatile storage used in SIM cards and flash drives where data can be electronically wiped and updated.

Peripherals

External hardware I/O devices (like keyboards, mice, printers, and external disk drives) connected to the computer but distinct from the core CPU.

I/O Controllers

Hardware interfaces that allow external devices (such as a keyboard, mouse, or VDU) to communicate directly with the processor.

Secondary Storage

Non-volatile, long-term storage mediums (such as HDDs, SSDs, optical discs, and flash drives) used to keep programs and data permanently.