Central Processing Unit and Architecture

Vocabulary flashcards defining key terms, registers, buses, ports, and architecture components from Computer Science 9618 Paper 1 notes.

Von Neumann Architecture

A model of a computer system consisting of a single, shared memory for both program instructions and data.

Stored Program Concept

A feature of the Von Neumann model where instructions and data are stored together in the same memory space / in main memory.

Control Unit (CU)

A CPU component that coordinates and synchronizes actions, sends/receives control signals, and manages the fetching, decoding, and execution of instructions.

Arithmetic Logic Unit (ALU)

A CPU unit designed to perform integer calculations, including arithmetic operations (+, -, *, /), bit shifting operations, and logic operations (AND, OR, XOR).

OPERAND

The part of a computer instruction which specifies what data is to be processed.

OPCODE

The instruction that is executed by the CPU.

Registers

Small pieces of memory that are part of the processor used for temporary storage of data which is about to be or has been processed.

Special Purpose Registers

Registers specialized for a specific use that hold the status of a program and can only be used by certain instructions.

General Purpose Registers

Registers that hold temporary data while performing operations and can be used for any purpose by most instructions.

Program Counter (PC)

A special purpose register that stores the address of the next instruction to be fetched.

Memory Address Register (MAR)

A register that stores the memory address where data is to be read from.

Memory Data Register (MDR)

A register that stores data that has just been read from memory or is being transferred.

Current Instruction Register (CIR)

A register that stores the instruction that is currently being executed.

Index Register (IX)

A register used in indexed or indirect addressing to store a value that is added to an address to give another address.

Accumulator (ACC)

A general purpose register where data is worked on and manipulated during operations.

Status Register (SR)

A register containing individual bits or flags that can be referenced to indicate a state or event following arithmetic or logical operations.

System Clock

A small part of the computer that sends out regular electrical pulses or timing signals to synchronize operations and process them in sequence.

Immediate Access Store (IAS)

A volatile part of RAM with fast access times that holds data, instructions, and programs currently in use by the computer.

Data Bus

A bi-directional bus that carries data back and forth between the processor and memory.

Address Bus

A uni-directional bus that carries signals related to memory addresses from the processor to memory or other components.

Control Bus

A bus that carries control signals (such as Interrupt, Timing, Read, and Write signals) sent by the Control Unit to coordinate component actions.

Data Bus Width

The width of a bus that determines the number of bits that can be simultaneously transferred, improving processing speed when increased.

Clock Speed

The frequency measured in GHz that dictates the number of Fetch-Execute cycles/instructions that can be executed per second.

Cache Memory

Fast access memory close to the CPU made of SRAM that stores frequently used instructions and data to prevent CPU idling.

Universal Serial Bus (USB)

An industrial standard interface with a four-wired shielded cable (two for power/earth, two for data) supporting plug and play peripheral connections.

High-Definition Multimedia Interface (HDMI)

A modern digital interface supporting fast data transfer rates, HDCP security, and simultaneous stream transmission of uncompressed video and audio over a single cable.

Video Graphics Array (VGA)

A display standard introduced by IBM in 1987 supporting 640x480 resolution with 16 colors that transmits video signals using analog format over 15-pin D-sub connectors.

Interrupt

A signal sent from a source or device telling the processor that its attention is needed.

Interrupt Service Routine (ISR)

A specific routine called by the processor to handle an interrupt after saving current register contents to the stack.