Chapter 5 IO.ppt - Chapter Five INPUT\/OUTPUT 1 Outline Introduction External Devices I\/O Modules Techniques for I\/O operations Programmed I\/O

Chapter 5 IO.ppt - Chapter Five INPUT/OUTPUT 1 Outline...

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Chapter Five INPUT/OUTPUT 1
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Outline Introduction External Devices I/O Modules Techniques for I/O operations Programmed I/O Interrupt-Driven I/O Direct Memory Access I/O Channels and Processors
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Introduction The computer system’s I/O architecture is its interface to the outside world. This architecture provides a systematic means of Controlling interaction with the outside world and providing the operating system with the information it needs to manage I/O activity effectively
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Introduction It is the third key element (IO module) of a computer system next to processor and memory Each module interfaces to the system bus or central switch and controls one or more peripheral devices. It contains logic for performing a communication function between the peripheral and the bus
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Why IO MODULE??? Varity of methods of operation (with the processor) Slow/fast data transfer rate use different data formats and word lengths 5
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Generic Model of an I/O Module 6
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I/O module has two major functions Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links 7
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EXTERNAL DEVICES Human readable Machine readable Communication 8
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External Device An external device attaches to the computer by a link to an I/O module The link is used to exchange control, status, and data between the I/O module and the external device. An external device connected to an I/O module is often referred to as a peripheral device or, simply, a peripheral 9
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Categories Human readable: Suitable for communicating with the user Example: VDTs and printers Machine readable: Suitable for communicating with equipment Example: magnetic disk and tape systems, and sensors and actuators, such as are used in a robotics application Communication: Suitable for communicating with remote devices 10
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Block Diagram of an External Device 11
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Control signals Determine the function that the device will perform, such as : Send data to the I/O module (INPUT or READ), Accept data from the I/O module (OUTPUT or WRITE), Report status perform some control function particular to the device (e.g., position a disk head).
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  • Fall '19
  • Central processing unit, Input device

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