CPU Structure & Instruction

CPU

The Central Processing Unit is the main part of a computer that processes instructions and controls operations.

Control Unit (CU)

Controls the flow of data and instructions within the CPU.

Arithmetic Logic Unit (ALU)

Performs arithmetic operations like addition and subtraction and logical operations.

Registers

Small, fast storage locations inside the CPU used to hold data temporarily.

Program Counter

Stores the address of the next instruction to be executed.

Instruction Register

Holds the current instruction being processed by the CPU.

Instruction cycle

The sequence of steps the CPU follows to execute an instruction.

Fetch stage

The CPU retrieves an instruction from memory.

Decode stage

The CPU interprets the instruction to understand what action is needed.

Execute stage

The CPU performs the operation specified by the instruction.

Store (Write-back) Stage

The result of execution is stored in a register or memory.

Pipelining

A technique where multiple instructions are processed at the same time in different stages.

Pipeline Hazard

A problem that occurs when instructions interfere with each other in a pipeline.

Structural Hazard

Occurs when hardware resources are insufficient to support multiple instructions.

Data Hazard

Happens when an instruction depends on data from a previous instruction.

Control Hazard

Occurs when the CPU cannot decide the next instruction due to branching.

RISC

Reduced Instruction Set Computer uses simple instructions for faster execution.

CISC

Complex Instruction Set Computer uses complex instructions that perform multiple tasks.

Clock Cycle

A single timing pulse that synchronizes CPU operations.

Throughput

The number of instructions completed by the CPU in a given time.