Input/Output

Question 1

what is a device controller?

Answer 1

electronic circuit capable of operating a device using binary signals

Question 2

to start an I/O operation, the driver ________

Answer 2

writes the opcode into the opcode register

Question 3

Prior to starting an I/O operation, the busy flag must be ______

Answer 3

FALSE

Question 4

When interrupts are used, the driver process is blocked while _______

Answer 4

data is being transferred between the device and controller buffer

Question 5

a DMA controller is a ___________

Answer 5

hardware device capable of reading and writing to main memory

Question 6

a DMA transfers data between _______

Answer 6

a device controller and main memory

Question 7

when is polling more useful than interrupts?

Answer 7

in real time systems where only 1 process is running

Question 8

The CPU time needed to process an I/O instruction is unpredictable with _____.

Answer 8

polling

Question 9

The buffer in a device controller decouples _____.

Answer 9

the device from the driver

Question 10

what is “cooked” input mode?

Answer 10

special characters do not appear in the buffer

Question 11

what is a disk block cache?

Answer 11

a set of main memory buffers that contain the most recently accessed disk blocks

Question 12

how are disk block caches organized?

Answer 12

hashing is used

Question 13

The list of free buffers is not accessed when _____.

Answer 13

a currently resident block is accessed

Question 14

what is the seek time?

Answer 14

the time to move the r/w head to the track containing the desired data

Question 15

what is rotational delay?

Answer 15

the time to wait for the desired data item to pass under the r/w head

Question 16

what is data transfer time?

Answer 16

the time to transfer the desired number of bits to or from the disk

Question 17

what is peak data transfer rate?

Answer 17

the rate data can be streamed once positioned

Question 18

what is sustained data rate?

Answer 18

the rate which data can be streamed including seek times and rotational delay

Question 19

Data on a magnetic disk is accessed in units of _____.

Answer 19

Sectors

Question 20

The time to seek from one track to another depends on the _____.

Answer 20

number of tracks on the disk

Question 21

what is shortest seek time first algorithm?

Answer 21

prioritizes data access requests based on the shortest seek time

Question 22

what is the scan scheduling algorithm?

Answer 22

basically works like an elevator going up and down servicing requests at every track in order. kinda like round robin

Question 23

what is a parity bit?

Answer 23

a bit added to a string of bits to ensure that the total number of 1’s is even or odd

Question 24

what is the difference between sector forwarding and sector slipping?

Answer 24

sector forwarding is a remapping…sector slipping is a shift to move away from the bad sector

Question 25

Striping is a technique to improve _____ of a RAID.

Answer 25

performance

Question 26

Adding redundant data in the form of parity or an ECC improves _____ of a RAID.

Answer 26

reliability