Thursday 12 December 2013

~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


















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