Final test

Question 1

What did the earliest electronic computers resemble?

Answer 1

A calculator.

Question 2

Modern computers also arrange for the processor to control external devices.

Answer 2

T

Question 3

The earliest external devices attached to computers consisted of independent unites that operated under control of the CPU.

Answer 3

T

Question 4

An interface between a computer and an external device is classified as parallel.

Answer 4

T

Question 5

Control functions for most devices are primar.

Answer 5

F

Question 6

The digital signals used internally by a processor are not sufficient for what?

Answer 6

Communication with an external device

Question 7

What is interface controllers?

Answer 7

The hardware that provides the interface to an external device.

Question 8

Serial interface refers to the number of parallel wires an interface uses.

Answer 8

F

Question 9

The chief disadvantage of parallel interface is an increased delay.

Answer 9

F

Question 10

What is self-clocking?

Answer 10

A mechanism in which signals sent across an interface contain information that allows the receiver to determine exactly how the sender encoded the data.

Question 11

What is the chief advantage of serial interface?

Answer 11

Few wires.

Question 12

What two methods accommodate bidirectional transfer?

Answer 12

Full-duplex and half-duplex interaction.

Question 13

Each integrated circuit has a variable number of pins that provide external connections.

Answer 13

F

Question 14

Throughput is usually measured in megabytes er second.

Answer 14

F

Question 15

What do multiplexor and demultiplexors describe.

Answer 15

Hardware that handles data multiplexing.

Question 16

What is the difference between latency and throughput?

Answer 16

Latency is the delay between when a bit is sent and the bit is received. Throughput is the number of bits that can be transferred per unit time.

Question 17

Which interface offers more performance than any other cominbation?

Answer 17

Full-duplex, parallel interface.

Question 18

Multiplexing is used to construct an I/O interface that can transfer arbitrary amounts of data over a fixed number of parallel wires.

Answer 18

T

Question 19

What does multiplexing do?

Answer 19

Construct an I/O interface that can transfer arbitrary amounts of data over a fixed number of parallel wires.

Question 20

A processor does not access external devices directly.

Answer 20

T

Question 21

How does a processor access external devices?

Answer 21

It uses a programming interface to pass requests to an inteface controller.

Question 22

A memory bus is intended to disconnect a processor with a memory system.

Answer 22

F

Question 23

What is a bus?

Answer 23

A digital communication mechanism that allows two or more functional units to transfer control signals or data.

Question 24

A standardized bus, means the specifications are available.

Answer 24

T

Question 25

The notion of bus is not broad enough to encompass most external connections.

Answer 25

T

Question 26

What does the term proprietary mean?

Answer 26

The design is owned by a private company and not available for use by other companies.

Question 27

All computer systems contain only one bus.

Answer 27

F

Question 28

Most buses are shared.

Answer 28

T

Question 29

The most straight forward busses are classified as what?

Answer 29

Passive.

Question 30

What does it mean for a bus to be shared?

Answer 30

A single bus is used to connect the procesor to a set of I/O devices.

Question 31

What is an internal bus?

Answer 31

A bus that is not visible to the computer's owner.

Question 32

Attaching a device to a bus is nontrivial.

Answer 32

T

Question 33

What does a bus use to determine when a given device can use the bus?

Answer 33

Access protocol

Question 34

What are the wires that comprise a bus called?

Answer 34

Lines.

Question 35

A bus only supports fetch and store operations

Answer 35

F

Question 36

Buses do not use the fetch-store paradign.

Answer 36

F

Question 37

What techniques is especially helpful in reducing the number of lines in a bus?

Answer 37

multiplexing.

Question 38

Address and data values are multiplexed over a processor.

Answer 38

F

Question 39

Addresses and data values are multiplexed over a bus.

Answer 39

T

Question 40

Although an interface receives all requests that pass across the bus, the interface only responds to requests that contain an address for which the interface has been configured.

Answer 40

T

Question 41

To avoid memory configuration problems, architects can place memory on small circuit boards that each plug into a socket on the bus interface.

Answer 41

F

Question 42

What do most bus protocols use to detect an unassigned address?

Answer 42

A timeout mechanism

Question 43

What is a buss address conflict?

Answer 43

A bus error that results when interfaces are misconfigured so they respond to the same address.

Question 44

What is an unassigned address bus error?

Answer 44

A processor attempts to access an address that has not been configured into any interface.

Question 45

What is the main goal of a bus?

Answer 45

???

Question 46

Although the bus operations are named fetch and store, a device interface is not a memory.

Answer 46

T

Question 47

What does it mean for an address to be asymmetric?

Answer 47

If it defines fetch, but not store, or vice versa.

Question 48

We call the specification for a bus an address map.

Answer 48

T

Question 49

What is an address map?

Answer 49

Part of the specifications for a bus.

Question 50

When an address space is not contiguous it is said to have gaps in the address space.

Answer 50

F (holes)

Question 51

Unlike a conventional device a bridge does not answer requests directly.

Answer 51

T

Question 52

What is one of the two advantages of using a bridge?

Answer 52

Lower cost.

Question 53

What is a bridge?

Answer 53

A hardware device that interconnects two buses and maps address between them.

Question 54

The goal of using a bridge is to make the memory addresses mirror the two underlying buses?

Answer 54

???

Question 55

What is one disadvantage of abus?

Answer 55

Bus hardware can only perform one transfer at a time.

Question 56

What is switching fabrics?

Answer 56

Technology that permits multiple transfers to occur simultaneously.

Question 57

Each bus never provides a protocol that attached devices use to access the bus.

Answer 57

F

Question 58

The basic mechanisms of I/O are difficult to specify.

Answer 58

F

Question 59

The earliest computers took a straightforward approach to I/O.

Answer 59

T

Question 60

To prevent problems with synchronization, programmed I/O relies on what?

Answer 60

Synchronization

Question 61

Polling is the basic form of synchronization that a processor uses with an IO device.

Answer 61

T

Question 62

What do you call thebasic form of sychronization that a processor uses with an I.O device?

Answer 62

Polling

Question 63

What does a polling processor require?

Answer 63

The processor to repeatedly ask the device whether an operation has completed before the processor starts the next operation.

Question 64

Control and Status Registers refer to the set of busses a device uses.

Answer 64

F

Question 65

The chief advantage of a programmed I/O architecture arises from the economic benefit.

Answer 65

T

Question 66

What does a control register correspond to?

Answer 66

A contiguous set of addresses.

Question 67

What does the term Control and Status Registers refer to?

Answer 67

The set of addresses that a device uses.

Question 68

The central premise of interrupt-driven I/O is instead of wasting time polling a processors should be performing other operations while the I/O device is working.

Answer 68

T

Question 69

What is one approach that emerged as a superior way to the mismatch between I/O and processor speeds?

Answer 69

Interrupts.

Question 70

A bus must support two -way communication.

Answer 70

T

Question 71

An interrupt permanently borrows the processor to handle an I/O device.

Answer 71

F

Question 72

Polling uses an asynchronous style of programming. Interrupts use a synchronous style of programming.

Answer 72

F

Question 73

What happens when an interrupt occurs?

Answer 73

The hardware saves the state of the computation and restarts the computation when interrupt processing finishes.

Question 74

how many steps are there to handling an interrupt?

Answer 74

Five.

Question 75

To handle an interrupt a processor takes five steps. Name one of the steps.

Answer 75

Save the current execution state.

Question 76

A computer can have many devices, including multiple copies of the same type of device.

Answer 76

T

Question 77

What upgrade in processors design has enabled the processor to be programmed to respond to the most important process first?

Answer 77

???

Question 78

A processor that has interrupt priority levels can only have one device assigned any given interrupt priority level.

Answer 78

T

Question 79

When operating a priority level K, a processor can be interrupted by a device that has been assigned any level K.

Answer 79

F

Question 80

What is manual interrupt assignment?

Answer 80

A person configures both the hardware and software.

Question 81

What is one of the two ways interrupt assignments are made?

Answer 81

Fixed, manual assignment used on small, embedded system.s

Question 82

What kind of computers are Automated Assignments used on?

Answer 82

General-purpose computer, such as a PC.

Question 83

Architects refer to devices that can operate with direct help from the processor as smart devices.

Answer 83

F

Question 84

Direct Memory Access (DMA) allows a smart I/O device to access memory directly.

Answer 84

T

Question 85

What is a soft error?

Answer 85

The processor must retry the operation to determine whether an error was temporary or permanent.

Question 86

The technology used to start a new operation without delay is known as operation chaining.

Answer 86

T

Question 87

What term is used to capture the idea of diving a large block of incoming data into multiple small buffers?

Answer 87

scatter read

Question 88

What are input and output devices.

Answer 88

Ways to connect computers to external devices.