DMA controllers

.

a. do not ulize an addional, special purpose, processor

b. are a nonstandard component in PCs of today

c. can steal memory access cycles from the main CPU

d. can access main memory at the same me as the main CPU

The correct answer is: can steal memory access cycles from the main CPU

A character-stream device

.

a. transfers data in blocks of bytes

b. transfers data a byte at a me

c. is a device such as a disk drive

d. is similar to a random access device

The correct answer is: transfers data a byte at a me

I/O accesses a block device as a simple array of blocks.

a. Raw

b. Stream

c. Indirect

d. Cooked

The correct answer is: Raw

Which of the following allocaon methods ensures that only one access is needed to get a disk block using direct access?

a. linked allocaon

b. indexed allocaon

c. hashed allocaon

d. conguous allocaon

The correct answer is: conguous allocaon

Which of the following is true of a blocking system call?

a. The applicaon connues to execute its code when the call is issued.

b. The call returns immediately without waing for the I/O to complete.

c. The execuon of the applicaon is suspended when the call is issued.

d. Blocking applicaon code is harder to understand than non-blocking applicaon code.

The correct answer is: The execuon of the applicaon is suspended when the call is

issued.

Consider a disk queue holding requests to the following cylinders in the listed order: 116, 22, 3, 11, 75, 185, 100, 87.

Using the SSTF scheduling algorithm, what is the order in which the requests are serviced, assuming the disk head is at

cylinder 88 and moving upward through the cylinders?