Lecture Notes: Computer System Architecture

Overview

This lecture focuses on categorizing computer systems based on the number of general-purpose processors they use, exploring single processor systems, multiprocessor systems, and clustered systems.

Types of Computer Systems

1. Single Processor Systems

• Main CPU: Executes general-purpose instruction sets and instructions from user processes.
• Special-Purpose Processors: Perform device-specific tasks (e.g., microprocessor in a keyboard for keystroke conversion).
• Definition Rationale: Named 'single processor' due to having only one general-purpose processor, despite the presence of special-purpose processors.

2. Multiprocessor Systems

• Characteristics: Contains two or more processors, also known as parallel or tightly coupled systems.
• Communication: Processors are in close communication, sharing computer resources such as bus, clock, memory, and peripherals.
• Advantages:
  • Increased Throughput: Higher performance due to parallel processing.
  • Economy of Scale: More economic as resources are shared among processors.
  • Increased Reliability: System continues functioning even if one processor fails.

Types of Multiprocessing Systems

• Symmetric Multiprocessing (SMP):
  • All CPUs are similar and participate equally in executing tasks.
• Asymmetric Multiprocessing (AMP):
  • Master-slave approach where the master CPU assigns tasks to slave CPUs.
  • Master monitors the system and assigns tasks to CPUs.

3. Clustered Systems

• Definition: Gather multiple CPUs to perform computational work by coupling two or more individual systems.
• High Availability: Multiple systems ensure continued operation even if one or more systems fail.

Structuring of Clustered Systems

• Asymmetric Structure:
  • One machine is on hot standby mode monitoring others, stepping in if a failure occurs.
• Symmetric Structure:
  • Multiple hosts run applications and monitor each other, allowing for efficient resource use.

Summary

• Single Processor Systems: Defined by one general-purpose processor with additional special-purpose processors for device-specific tasks.
• Multiprocessor Systems: Involves multiple processors for increased performance, economic benefit, and reliability.
• Clustered Systems: Involves multiple coupled systems with high availability, structured either symmetrically or asymmetrically.

Understanding these architectures provides insights into how computer systems can be optimized for performance, reliability, and economic efficiency.