CPU Architecture: Flynn's Taxonomy

CPU Architecture

• ** Flynn's Taxonomy**: classification of CPU architectures based on the number of instruction streams and data streams:
  • SISD (Single Instruction, Single Data): single instruction operates on single data element (traditional von Neumann architecture)
  • SIMD (Single Instruction, Multiple Data): single instruction operates on multiple data elements (vector processing)
  • MISD (Multiple Instruction, Single Data): multiple instructions operate on single data element (rarely used)
  • MIMD (Multiple Instruction, Multiple Data): multiple instructions operate on multiple data elements (parallel processing)
• CPU Components:
  • Control Unit: retrieves and decodes instructions, generates control signals
  • Arithmetic Logic Unit (ALU): performs arithmetic and logical operations
  • Registers: small amount of on-chip memory for storing data and instructions

Instruction Pipeline

• Instruction Pipeline Stages:
  1. Instruction Fetch: retrieve instruction from memory
  2. Instruction Decode: decode instruction into opcode, operands, and control signals
  3. Operand Fetch: retrieve operands from registers or memory
  4. Execution: execute instruction using ALU
  5. Memory Access: access memory for load/store operations
  6. Write Back: write results back to registers
• Pipeline Hazards:
  • Structural Hazards: conflicts between instructions for shared resources (e.g., registers)
  • Data Hazards: dependencies between instructions for data operands
  • Control Hazards: conflicts between instructions for control flow (e.g., branches)
• Pipeline Optimization Techniques:
  • Instruction-Level Parallelism (ILP): execute multiple instructions concurrently
  • Out-of-Order Execution: execute instructions out of original order to reduce dependencies
  • Register Renaming: rename registers to reduce dependencies and improve ILP

CPU Architecture

• Flynn's Taxonomy categorizes CPU architectures into four types based on the number of instruction streams and data streams.
• SISD (Single Instruction, Single Data) architecture has a single instruction operating on a single data element, typical of traditional von Neumann architecture.
• SIMD (Single Instruction, Multiple Data) architecture has a single instruction operating on multiple data elements, used in vector processing.
• MISD (Multiple Instruction, Single Data) architecture has multiple instructions operating on a single data element, rarely used.
• MIMD (Multiple Instruction, Multiple Data) architecture has multiple instructions operating on multiple data elements, used in parallel processing.

CPU Components

• The Control Unit retrieves and decodes instructions, generating control signals.
• The Arithmetic Logic Unit (ALU) performs arithmetic and logical operations.
• Registers are small amounts of on-chip memory for storing data and instructions.

Instruction Pipeline

• The Instruction Pipeline is divided into six stages: Instruction Fetch, Instruction Decode, Operand Fetch, Execution, Memory Access, and Write Back.
• Instruction Fetch retrieves an instruction from memory.
• Instruction Decode decodes the instruction into an opcode, operands, and control signals.
• Operand Fetch retrieves operands from registers or memory.
• Execution executes the instruction using the ALU.
• Memory Access accesses memory for load/store operations.
• Write Back writes results back to registers.

Pipeline Hazards

• Structural Hazards occur when instructions conflict for shared resources, such as registers.
• Data Hazards occur when instructions have dependencies for data operands.
• Control Hazards occur when instructions conflict for control flow, such as branches.

Pipeline Optimization Techniques

• Instruction-Level Parallelism (ILP) executes multiple instructions concurrently.
• Out-of-Order Execution executes instructions out of their original order to reduce dependencies.
• Register Renaming renames registers to reduce dependencies and improve ILP.

Classification of CPU architectures based on instruction and data streams, including SISD, SIMD, and MISD. Learn about Flynn's Taxonomy and its applications.