I/O Management Flashcards

1
Q

How is communicating with I/O devices handled?

A

Communication takes place over a cable known as a Bus, and is operated by Controllers.

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2
Q

What are the 4 types of registers used in I/O communication?

A

Data-In register, Data-out register, Status Register, Control Register

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3
Q

what is stored in the Control Register?

A

Commands to the device such as save, write, transfer, and read commands.

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4
Q

How does Port based I/O work?

A

Special Instructions are used to transfer a small number of bytes to an I/O bus address

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5
Q

How does Memory-Mapped I/O work?

A

Standard Memory Instruction used by treating the device as memory and writing/reading from the location.

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6
Q

What is Polling?

A

CPU checks controller status, when status is ready CPU writes to Data Out register then Controller. CPU is much faster than I/O so most Poll’s are unsuccessful.

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7
Q

What are I/O Interrupts?

A

When the I/O device wants to give an input its send san interrupt to the CPU in order to initiate the appropriate process.

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7
Q

What are I/O Interrupts?

A

When the I/O device wants to give an input its send san interrupt to the CPU in order to initiate the appropriate process.

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8
Q

In which circumstances is polling appropriate?

A

If the controller and device are fast in relation to the CPU, if the I/O rate is high, if some I/O data can be ignored, if the CPU is not engaged in other processes.

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9
Q

How are large data transfers handled?

A

These are inefficient if done byte by byte, this work is offloaded to a special purpose processor (Direct Memory Access Controller) so that the CPU can handle other processes.

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10
Q

How does the Direct Memory Access Controller work?

A

CPU writes a command block to memory specifying source and destination of transfer. DMA controllers can handle multiple transfers at the same time.

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11
Q

How do Device Drivers Function?

A

Device Drivers hide the differences between various device controllers by defining an interface between the OS and I/O devices. Device Drivers are loaded as modules into the kernel.

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12
Q

Which devices are Character I/O devices?

A

Keyboard, mouse, microphones, and speakers

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13
Q

How is data sent to Character I/O’s?

A

Data is sent in a stream of bytes. Characters must be processed in the order they arrive in the stream.

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14
Q

Which interfaces are used by Character I/O’s

A

Get operation, Put operation, Libraries for line-by-line access.

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15
Q

Which devices are Block I/O?

A

Non-Volatile Storage devices

16
Q

How is data sent for Block I/O’s?

A

Data is transferred in Blocks, the order of the data doesn’t matter as long as everything is correct and uncorrupted. DMAC is used for transfer.

17
Q

How are memory mapped files handled?

A

Address range from disk is taken and mapped to memory, data is written to the memory and the CPU can synch the disk with memory at any time.

18
Q

Which interface instructions do Network I/O devices have?

A

Create and connect sockets, send and receive packets, select function, for determining status of sockets. System functions also included for checking if transfer is successful, and recovering form unsuccessful transfer.