~INPUT OUTPUT~

Input/Output Problems

• Computers have a wide variety of peripherals

• Many are not connected directly to system or expansion bus

• Most peripherals are slower than CPU and RAM; a few are faster

• Word length for peripherals may vary from the CPU

• Data format may vary (e.g., one word might include parity bits)

Generic Model of I/O Module

External Devices

• Human readable

 —Screen, printer, keyboard

   Machine readable 

 —Monitoring and control

•Communication

 —Modem 

 —Network Interface Card (NIC)

External Device Block Diagram

I/O Module Diagram

Three Techniques for Input of a Block of Data

Memory Mapped and Isolated I/O

 

Simple Interrupt Processing

Changes in Memory and Registers for an Interrupt

Typical DMA Module Diagram

DMA and Interrupt Breakpoints During an Instruction Cycle

DMA Configurations (1)

•Single Bus, Detached DMA controller

•Each transfer uses bus twice

—I/O to DMA then DMA to memory

•CPU is suspended twice

DMA Configurations (2)

•Single Bus, Integrated DMA controller

•Controller may support >1 device

•Each transfer uses bus once

—DMA to memory

•CPU is suspended once

DMA Configurations (3)

•Separate I/O Bus

•Bus supports all DMA enabled devices

•Each transfer uses bus once

—DMA to memory

•CPU is suspended once

DMA Usage of Systems Bus

I/O Channel Architecture

Simple FireWire Configuration

FireWire Protocol Stack

FireWire Subactions

ENJOY 

YOUR 

COMPUTER ORGANISATION

&

ARCHITECTURE

:)

-Muhammad Shakir-

B031310451