أسس معمارية الكمبيوتر

Introduction to Computer Architecture

• Computer architecture encompasses the visible attributes to programmers, such as instruction sets, data representation, and addressing techniques.
• Organization details the implementation of these features, including control signals, interfaces, and memory technologies.

Structure & Function

• Structure describes how components relate to each other.
• Function specifies how individual components work together within the structure.

Functional View

• All computer functions involve:
  • Data processing
  • Data storage
  • Data movement
  • Control

Operations

• Data Movement: Data transfer between the computer and the outside world.
• Storage: Temporary storage of data being processed.
• Processing: Processing of data from and to storage or I/O.
• Processing from storage to I/O: Transfer of data from storage to I/O.

The Computer - Top Level Structure

• Components include:
  • Input/Output (I/O)
  • Main memory
  • CPU

The Processor

• The CPU's purpose is to fetch and execute instructions.
• Key components:
  • Arithmetic Logic Unit (ALU)
  • Control Unit
  • Cache
  • Registers (PC, MAR, MDR, ACC)

Von Neumann Machines

• A fundamental computer architecture model.
• Data and program are stored in the same memory space.
• The machine can modify its own programs or internal data.

Von Neumann Machines (Continued)

• Stored-program concept for primary memory.
• Arithmetic and logic units
• Input and output devices
• Control units to interpret and execute stored programs and instructions.

Structure of Von Neumann Machine

• The von Neumann Machine consists of a CPU and primary memory along with I/O devices.
• The CPU holds the control unit, arithmetic logic unit (ALU), and registers.
• The primary memory holds the program instructions and data required for execution.
• I/O units (Input/output devices) provide interfaces for program input and output.

Computer Registers

• Registers are storage locations within the CPU.
• Examples include: Memory Buffer Register (MBR), Memory Address Register (MAR), Instruction Register (IR), Instruction Buffer Register, Program Counter (PC), Accumulator.

IBM Systems

• IBM is a major manufacturer of computer systems.
• Key milestones include the 701 and 702 computers, marking progress towards stored program computers and business applications.

Transistors

• Transistors replaced vacuum tubes, leading to smaller, cheaper, and more efficient computer components.
• Invented at Bell Labs, marking the second generation of computers.

Semiconductor Memory

• Semiconductor memory was developed in the 1970s.
• This memory could store large quantities of data compared to previous technologies.
• Its density was much higher as well.

Evolution of Intel Microprocessors

• Innovations in microprocessors led to significant improvements in computer processing power.
• Progress included advancements like the 4004 chip and the 8008 chip.
• Modern chips now have more complex capabilities and processing power.

Speeding it up

• Advanced techniques, such as branch prediction and data flow analysis, optimize instruction execution.
• Speculative execution predicts future instruction needs for fast process completion.

What is a Program?

• A program is a sequence of steps, each involving an arithmetic or logical operation.
• Each operation needs specific control signals.

Function of Control Unit

• A dedicated hardware segment for each program step.
• Unique codes specify each instruction.

Components

• CPU consists of control unit and arithmetic logic unit (ALU).
• Systems need input/output (I/O) mechanisms.
• Data and programs require temporary storage.

Instruction Cycle

• The instruction cycle has two main parts: fetch and execute.
• The fetch cycle retrieves the next instruction.
• The execute cycle performs the instruction.

Execute Cycle

• Processor-memory data transfer (between CPU and memory)
• Processor-I/O data transfer (between CPU and I/O modules)
• Data processing (arithmetic or logical operations on data)
• Control (changing the sequence of operations, like branching)

Interrupts

• Interrupt handles events such as hardware faults or I/O completion.
• Interrupts suspend current program execution.

Connecting

• Connecting various units with specific connections for each unit (memory, I/O, CPU).

1. Memory Connection

• Data transfer with address and control signals.

2. Input/Output Connection

• Data transfer with addresses and control signals (e.g., signals for disk operation).
• Interrupts signal completion or errors.

3. CPU Connection

• The CPU reads instructions and data.
• The CPU writes out processed data.
• The CPU sends signals to other units.
• The CPU processes interrupts.

Buses

• Buses act as communication pathways for components within a computer system.
• Common types of buses include control, address, and data buses.

What is a Bus?

• A communication pathway connecting devices.
• Types commonly grouped: data, control, address, power.

Address Bus

• Identifies memory locations.
• Width determines memory capacity.

Control Bus

• Carries control and timing signals.
• Examples include read/write signals and clock signals.

Memory Hierarchy

• Different levels of memory with varying access times and data storage capacities.
• A hierarchy exists between registers (fast) and secondary storage (slow).

Memory Hierarchy - Diagram

• Diagram shows different levels in decreasing access speeds.

Performance

• Access time, memory cycle time, and transfer rate affect performance.

Access Methods

• Sequential, direct, random, associative access methods.

Internal Memory

• Random access memory (RAM) is volatile memory.
• Dynamic RAM (DRAM) needs refreshing.
• Static RAM (SRAM) is faster but more expensive than DRAM.

Internal Memory (Continued)

• Volatile: Loses stored data when power is removed.
• Read-only memory (ROM) is non-volatile; stores essential information.

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