Communicating With Devices Interrupts

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Communicating With DevicesInterrupts

• Lecture 10.4
• Section 10.6

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Communicating Between Devices

• Device makes a
• request to the CPU
• by bringing request
• line HIGH

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Communicating Between Devices

• Processor takes the number provided by the
  encoder and uses it to switch MUX and deMUX

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Communicating Between Devices

• Using this number, CPU acknowledges the
  communication and conversation commences

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Communicating Between Devices

• Processor accepts information on Input lines
  and sends information on Output lines

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Communicating Between Devices

• Processor ends communication by bringing
  acknowledge line LOW. Device ends its request

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Communicating Between Devices

• Processor ends communication by bringing
  acknowledge line LOW. Device ends its request

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Communicating Between Devices
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Communicating Between Devices
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Communicating Between Devices
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68000 Interrupt Logic
A0 A1 A2
74138 Decoder
68000
IRQA
IP0 IP1 IP2
74148 Encoder
Peripheral
IRQ
Data Bus
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External Devices Interrupting a CPU
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State Diagram for the Interrupt Handler
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Interrupt Handler
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Interrupt Handler
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Interrupt Handler