HG

Ch2 x86 Microprocessor Architecture

Introduction to x86 Microprocessor Architecture

  • Overview of the material to be covered in Chapter Two.
  • Focus on understanding x86 architecture, its memory, and I/O operations.

Basic Hardware of x86 Assembly Language

  • Importance of microcomputer design in understanding assembly language.
  • The basic components include:
  • Microprocessor: the CPU that executes instructions.
  • Memory: where data and code are stored.
  • I/O: peripheral devices for external communication.
  • Buses: pathways (data bus, address bus, control bus) for communication between components.

Microprocessor Components

  • Arithmetic Logic Unit (ALU):
  • Performs arithmetic operations (addition, subtraction) and logic operations (AND, OR).
  • Control Unit:
  • Directs processor operation by interpreting instructions.
  • Clock:
  • Synchronizes operations within the CPU, measured in cycles.
  • Registers:
  • Small, fast storage locations within the CPU; accessed as 32-bit, 16-bit, or 8-bit memory.

Memory Management

  • Basic layout of the system: CPU, Memory, I/O, Buses.
  • Understanding how to read from memory using the address bus, control bus, and data bus:
  • Address Bus: Determines memory location to read/write.
  • Control Bus: Manages read/write commands.
  • Data Bus: Carries information between memory and CPU.
  • Example: If CPU wants to read a value, it uses the address bus to specify the address, requests data via the control bus, and receives it through the data bus.

Clock Cycle and Frequency

  • Clock Cycle:
  • Each CPU operation is synchronized to a clock cycle.
  • Frequency defines the speed, often expressed in megahertz (MHz) or gigahertz (GHz).
  • Example:
  • A clock speed of 1 GHz means the CPU can perform 1 billion cycles per second.

Instruction Cycle

  • Each instruction executed by the CPU follows a cycle:
  1. Fetch instruction from memory.
  2. Decode the instruction to identify action.
  3. Execute the instruction.

Instruction Types

  • Types of instructions handled by the CPU:
  • Data Transfer (e.g., MOV, PUSH, POP)
  • Arithmetic Operations (e.g., ADD, SUB)
  • Logical Operations (e.g., AND, OR)
  • Control Flow (e.g., JUMP, CALL, RETURN)

Pipelining and Parallel Processing

  • Concept of pipelining allows overlapping instruction processing stages:
  • While one instruction is executing, the next instruction can be fetched, reducing idle time.

Modes of Operation

  • Protected Mode:
  • Provides security and allows access to 4 GB of memory (2^32 address space).
  • Ensures memory protection against unsafe access.
  • Real Address Mode:
  • Allows smaller address space (1 MB, 2^20), lacks protection mechanisms.

Cache Memory

  • Cache Memory:
  • A small, fast memory located within the CPU for high-speed data storage and retrieval to minimize access time to slower main memory.
  • Hit/Miss ratio as a performance measure of cache efficiency:
  • Cache Hit: Data found in the cache.
  • Cache Miss: Data not found, requiring access to slower main memory.

Final Thoughts

  • Comprehensive understanding of microprocessor architecture is essential for working with assembly language.
  • Emphasis on how programs are loaded into memory and executed via the CPU.
  • Review of key concepts: Microprocessor, memory structure, bus types, clock cycles, instruction execution, and modes of operation.