Input output organisation

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Chapter 10Input/Output Organization
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Chapter Outline

• Asynchronous data transfers
• Programmed I/O
• Interrupts
• Direct Memory Access
• I/O Processors
• Serial Communication
• Serial Communication Standards

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Asynchronous Data Transfers
4
Source-initiated Data Transfer
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Destination-initiated Data Transfer
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Source-initiated Data Transfer with Handshaking
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Destination-initiated Data Transfer with
Handshaking
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Programmed I/O
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Example
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Example
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Example
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Example
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Example
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New Instructions
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New Control Signals

• IO differentiates I/O and memory accesses
• IO 1 for I/O access
• IO 0 for memory access

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New States and RTL Code
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CPU Modifications

• Modify register section

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CPU Modifications

• Modify register section
• Modify ALU

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CPU Modifications

• Modify register section
• Modify ALU
• Modify control unit (hard-wired)

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CPU Modifications

• Modify register section
• Modify ALU
• Modify control unit (hard-wired)
• Register and ALU sections unchanged

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CPU Modifications

• Modify register section
• Modify ALU
• Modify control unit (hard-wired)
• Register and ALU sections unchanged
• One new micro-operation DR ? Input Port

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Control Unit Changes
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Control Unit Changes - INC and CLR signals
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Control Unit Changes - INC and CLR signals
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Control Unit Changes - Memory Read Signal

• Memory Read READ IO

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Interrupts

• Polling

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Interrupts

• IRQ - Interrupt Request
• IACK - Interrupt Acknowledge

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Types of Interrupts

• External

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Types of Interrupts

• External
• Internal

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Types of Interrupts

• External
• Internal
• Software

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Processing Interrupts

• Do nothing (until the current instruction has
  been executed)

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Processing Interrupts

• Do nothing (until the current instruction has
  been executed)
• Get handler address (vectored)

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Processing Interrupts

• Do nothing (until the current instruction has
  been executed)
• Get handler address (vectored)
• Invoke handler routine

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Vectored Interrupt Hardware
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Non-vectored Interrupt Hardware
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Multiple Non-vectored Interrupts
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Daisy Chaining
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IACKin and IACKout
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Parallel Priority Interrupts
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CPU Modifications
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CPU Modifications
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Interrupt States
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Direct Memory Access
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DMA Controller
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DMA Transfer Modes

• Block/Burst Mode

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DMA Transfer Modes

• Block/Burst Mode
• Cycle Stealing Mode

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DMA Transfer Modes

• Block/Burst Mode
• Cycle Stealing Mode
• Transparent Mode

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CPU Modifications - Micro-operations
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CPU Modifications - Micro-operations
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CPU Modifications
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CPU Modifications
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I/O Processors
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I/O Processors - operations

• Block transfer commands

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I/O Processors - operations

• Block transfer commands
• ALU operations

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I/O Processors - operations

• Block transfer commands
• ALU operations
• Control commands

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Asynchronous Serial Communication

• bps - Bits Per Second (baud rate)

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Asynchronous Serial Communication

• bps - Bits Per Second (baud rate)
• start bit

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Asynchronous Serial Communication

• bps - Bits Per Second (baud rate)
• start bit
• parity bit

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Asynchronous Serial Communication

• bps - Bits Per Second (baud rate)
• start bit
• parity bit
• stop bit(s)

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Asynchronous Serial Communication

• bps - Bits Per Second (baud rate)
• start bit
• parity bit
• stop bit(s)
• bit time

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Asynchronous Serial Communication
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Synchronous Serial Communication - HDLC
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Universal Asynchronous Receiver/Transmitters
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UART Internal Configuration
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RS 232C Standard - Signals

• Request To Send
• Clear To Send
• Transmission Data
• Data Terminal Ready
• Data Set Ready
• Received Data
• Data Carrier Detect
• Ring Indicator
• Ground

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RS 232C Standard - Connection

• Use RTS, CTS, DTR, and DSR to verify that both
  devices are active

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RS 232C Standard - Connection

• Use RTS, CTS, DTR, and DSR to verify that both
  devices are active
• Use RI to indicate call status

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RS 232C Standard - Connection

• Use RTS, CTS, DTR, and DSR to verify that both
  devices are active
• Use RI to indicate call status
• Use DCD to establish connectivity

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RS 232C Standard - Connection

• Use RTS, CTS, DTR, and DSR to verify that both
  devices are active
• Use RI to indicate call status
• Use DCD to establish connectivity
• Use TD and RD to transfer data, and RTS and CTS
  to coordinate transfers

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RS 422 Standard - Signals
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Universal Serial Bus Standard

• Connects one port to several devices

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Universal Serial Bus Standard

• Connects one port to several devices
• Transfers data in packets
• Token packets
• Data packets
• Handshake packets
• Special Packets

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USB Packet Formats
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Summary

• Asynchronous data transfers
• Programmed I/O
• Interrupts
• Direct Memory Access
• I/O Processors
• Serial Communication
• Serial Communication Standards