OS_05

What is asynchronous transfer in principles of I/O software?

• The user process makes system call and goes to sleep until other process it wakes up.

• The CPU starts the transfer and goes off to do something else until the interrupt arrives.

• The user program starts system call to transfer and automatically suspended until the data are available in the buffer.

• None of the other choices

How many percent of the CPU time is wasted, when a computer system has enough room to hold two program and these programs are idle waiting for I/O half the time?

• 75%

• 25%

• 50%

• None of the other choices

How many categories can be the I/O devices roughly divided

• 3

• 4

• 2 (block devices and character devices)

• 1

The aspect of disk performance that represents the time it takes to position the head a the desired track is known as

• None of the other choices

• Access time

• Rotational delay

• Seek time

In a fixed magnetic disk, each circle is called a

• platter

• sector

• block

• track

The Linking technique that allows the file to appear in more than one directory are:

• Hard link

• Soft link

• Both hard link and symbolic link

• Symbolic link

Which is not a function of device drivers?

• To receive system call

• To accept abstract read and write request from device independent software above it and see that they are carried out

• To initialize the device, if needed

• To manage its power requirements and log events

The term __________ a specialized instruction set.

• Programmed I/O

• None of the other choices

• DMA characterizes a system configuration that includes and I/O module that is a separate processor with

• I/O device

Assuming that its takes 10 nsec to copy a byte, how much time does it take to completely rewrite the screen of a 1200 x 8000 pixel graphics with 24-bitcolor

• 288 micro-sec

• 288 msec

• 28.8 msec

• 28.8 micro-sec

The I/O technique where the processor busy waits for an I/O operation to complete is called:

• None of the above

• Interrupt-driven I/O

• Programmed I/O

• Direct Memory Access ( DMA)