OCR GCSE Computer Science Paper 1

CPU

Central Processing Unit, the main component of a computer that carries out program instructions.

ALU

Arithmetic Logic Unit, a component of the CPU that performs mathematical and logical operations.

Control Unit

The part of the CPU that coordinates the fetch-execute cycle and decodes instructions.

Cache

A small, fast type of memory that holds frequently accessed items, checked before RAM.

Registers

Ultra-small, ultra-fast storage locations within the CPU for temporary data and instructions.

MAR

Memory Address Register, holds the address of the memory location being accessed.

MDR

Memory Data Register, stores the actual data or instruction fetched from memory.

Program Counter

A register that holds the address of the next instruction to be fetched from memory.

Von Neumann Architecture

A computer architecture model that describes a system where the CPU executes instructions in a fetch-execute cycle.

Fetch-Execute Cycle

The process by which the CPU retrieves an instruction from memory, decodes it, and executes it.

Clock Speed

The rate at which a CPU can execute instructions, measured in gigahertz (GHz).

Cores

Independent processing units within a CPU that can execute instructions simultaneously.

Virtual Memory

A portion of secondary storage used as an extension of RAM when it is full.

Primary Storage

Memory directly connected to the CPU, including RAM and ROM.

Secondary Storage

Non-volatile storage used for long-term data retention, such as hard drives and SSDs.

RAM

Random Access Memory, volatile memory that temporarily stores data and programs while the computer is on.

ROM

Read-Only Memory, non-volatile memory that contains essential startup instructions for the computer.

Magnetic Storage

A type of secondary storage that uses magnetic polarity to represent data, e.g., hard disk drives (HDDs).

Optical Storage

A type of secondary storage that uses light to read and write data, e.g., DVDs.

Solid-State Storage

A type of secondary storage that uses flash memory with no moving parts, e.g., SSDs.

Bit

The smallest unit of data in computing, representing a binary value of 0 or 1.

Nibble

A group of four bits.

Byte

A group of eight bits, equivalent to two nibbles.

Kilobyte

A unit of digital information equal to approximately 1,000 bytes.

Binary

A base-2 numeral system that uses only two digits, 0 and 1.

Hexadecimal

A base-16 numeral system that uses digits 0-9 and letters A-F to represent values.

Denary

The base-10 numeral system, commonly used in everyday counting.

Binary Addition

The process of adding binary numbers, following specific rules for carrying over.