OCR GCSE Computer Science J277 - 1.1 Systems Architecture Flashcards

A set of 31 vocabulary flashcards covering key concepts from OCR GCSE Computer Science J277 - 1.1 Systems Architecture.

CPU (Central Processing Unit)

Processes instructions and controls the operation of a computer.

Main Purpose of the CPU

To fetch, decode and execute instructions.

Fetch-Execute Cycle

The repeated process in which the CPU fetches an instruction, decodes it and executes it.

Fetch Stage

The stage where the CPU gets the next instruction from memory.

Decode Stage

The stage where the Control Unit works out what the instruction means and what must be done.

Execute Stage

The stage where the CPU carries out the instruction.

ALU (Arithmetic Logic Unit)

Performs arithmetic calculations and logical operations.

CU (Control Unit)

Coordinates the CPU and controls the flow of data and instructions.

Cache

Small, fast memory close to or inside the CPU that stores frequently or recently used data and instructions.

Cache Performance Benefit

More frequently used data and instructions can be accessed quickly instead of being fetched from slower main memory.

Register

A very small, very fast storage location inside the CPU.

Von Neumann Architecture

A computer architecture in which instructions and data are stored in memory for the CPU to process.

MAR (Memory Address Register)

Stores the address of the memory location currently being accessed.

MAR Content Type

An address.

MDR (Memory Data Register)

Stores data or an instruction being transferred to or from memory.

MDR Content Type

Data or an instruction, not an address.

Program Counter (PC)

Stores the address of the next instruction to be fetched.

Accumulator (ACC)

Stores results of calculations or data currently being processed by the ALU.

Difference Between MAR and MDR

The MAR stores a memory address; the MDR stores the data or instruction at a memory location.

Clock Speed

The number of CPU clock cycles per second, measured in hertz (Hz).

Clock Speed Performance Effect

More instructions may be processed per second, so performance can increase.

Clock Speed Disadvantage

It can increase power consumption and heat production.

Cache Size Performance Effect

More useful data and instructions can be accessed quickly, reducing the need to access slower main memory.

CPU Core

An individual processing unit within a CPU that can execute instructions.

Multiple CPU Cores Effect

More instructions or tasks may be processed at the same time when software can use multiple cores.

Multiple Cores Limitation

Some programs or tasks cannot be divided efficiently between multiple cores.

OCR Required CPU Characteristics

Clock speed, cache size and number of cores.

Embedded System

A computer system built into a larger device to perform a specific function.

Embedded System Characteristic

It is designed for a limited or specific set of functions rather than general-purpose computing.

Embedded System Examples

Washing-machine controller, car engine-management system, traffic-light controller, microwave controller or smart thermostat.

Embedded System Resource Design

Designed with limited hardware because they only need enough processing, memory and storage for their specific purpose, helping reduce cost, size and power use.