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I/O Systems in OPERATING SYSTEM Presented by Shweta Patel

Operating system-INPUT/OUTP (by shweta patel)

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Page 1: Operating system-INPUT/OUTP (by shweta patel)

I/O Systemsin

OPERATING SYSTEM

Presented by

Shweta Patel

Page 2: Operating system-INPUT/OUTP (by shweta patel)

OBJECTIVES

•Understanding the various I/O devices and their characteristics.

•Understanding the role of device drivers.

•Understanding the transformation of I/O request to h/w operation.

Page 3: Operating system-INPUT/OUTP (by shweta patel)

VARIOUS I/O DEVICES

PURPOSE ACCESS MODE EXAMPLES

INPUT

Sequential Keyboard, Mouse

Random Disks

PRINT

Sequential Printers

Random Disks

STORAGE

Sequential Tapes, Disks

Random Disks

Page 4: Operating system-INPUT/OUTP (by shweta patel)

CHARACTERISTICS OF I/O DEVICES

Page 5: Operating system-INPUT/OUTP (by shweta patel)

DEVICE DRIVERS•Program in the operating system ,

responsible for managing the h/w device attached to the system.

•Insulates the applications from having to know the details about the physical connections , protocols and signals required to communicate with a device.

•The application doesn’t have to know the physical address of the port.

Page 6: Operating system-INPUT/OUTP (by shweta patel)

•In general, n applications can communicate with m devices using a common device driver.

•Employs a mapping table to communicate with a specific device.

•If the driver is using more than one device , then drivers can use resource table.

•To seek a device driver , system calls are used .

Page 7: Operating system-INPUT/OUTP (by shweta patel)

Device driver

Mapping table

Resource table

Channel

Device 1

Device 2

Device 3

Device Driver Implementation

Page 8: Operating system-INPUT/OUTP (by shweta patel)

TRANSFORMING I/O to H/W OPERATION

Ex. Reading a file from disk

•The application refers the file by the filename.

•A file system maps the file name to identify the space allocation for the file.

•The first part of the file (c:) identifies the specific h/w device.

Page 9: Operating system-INPUT/OUTP (by shweta patel)

STEPS

▫Determine device holding file. ▫Translate name to device representation.

▫Physically read data from disk into buffer.

▫Make data available to requesting application .

▫Return control to process.

Page 10: Operating system-INPUT/OUTP (by shweta patel)

LIFE CYCLE OF AN I/O REQUEST

Page 11: Operating system-INPUT/OUTP (by shweta patel)

TWO I/O METHODS

SYNCHRONOUS

ASYNCHRONOUS

Page 12: Operating system-INPUT/OUTP (by shweta patel)

THANK YOU !!