IT 342 exam 4(20-23) EXAM also covers
previous chapters Answered
Correctly!!!!
I/O objectives CORRECT ANSWERS Efficiency - I/O is the bottleneck compared to
CPU
Generality - Handle all devices the same
Role of the operating system on the I/O? CORRECT ANSWERS manage and control
I/O operations and devices
I/O categories (3 total) CORRECT ANSWERS Human readable - printers, monitors,
mouse
Machine readable - disk drives, USB keys, sensors
Communication - remote devices like modems
What is a trend in I/O? CORRECT ANSWERS standards for Software and hardware
interfaces
What is a bus? CORRECT ANSWERS set of wires with protocols like IDE disk
controllers
What is a daisy chain? CORRECT ANSWERS when you take different peripheral
devices and connect them to each other. like disk drives
What are the methods for I/O to talk to PC (3)? CORRECT ANSWERS polling - cpu
checks the device periodically
interrupts - peripheral sends a signal to be serviced
DMA - controller can access the memory without using the CPU
What are the 3 blocking options for the I/O? CORRECT ANSWERS Blocking I/O - when
I/O request, process goes to waiting queue
Non-blocking I/O - process is not blocked, and continues
Asynchronous I/O - process continues other tasks and starts back up after I/O is done.
, What is the buffer? CORRECT ANSWERS memory storage which is used to store
temporary data while it travels form one place to a different one.
What are two benefits of buffering? CORRECT ANSWERS allows for different speeds
in devices
makes transfer much smaller
What are the 3 types of buffers? CORRECT ANSWERS single buffer
double buffer
circular buffer - more than one buffer, but oldest data is overwritten
What does disk management include? CORRECT ANSWERS scheduling
buffering
swap space management
What are some attributes of a disk? (3) CORRECT ANSWERS large logical array of
blocks
512 bytes per block often
blocks are separated to sectors
Why is mapping logical to physical so hard for disks? CORRECT ANSWERS
conversion is hard - there could be defective sectors or sectors on a track that are not
consistent.
What is access time? CORRECT ANSWERS total time to fetch the data. It includes:
seek time - time for disk arm to move to cylinder
rotational latency - time for disk arm to get to the right sector
What is disk scheduling? CORRECT ANSWERS a thing the Os manages - this defines
how files are transferred from the disk
What are 6 disk scheduling algorithms? CORRECT ANSWERS First come first served
shortest seek time first
scan
previous chapters Answered
Correctly!!!!
I/O objectives CORRECT ANSWERS Efficiency - I/O is the bottleneck compared to
CPU
Generality - Handle all devices the same
Role of the operating system on the I/O? CORRECT ANSWERS manage and control
I/O operations and devices
I/O categories (3 total) CORRECT ANSWERS Human readable - printers, monitors,
mouse
Machine readable - disk drives, USB keys, sensors
Communication - remote devices like modems
What is a trend in I/O? CORRECT ANSWERS standards for Software and hardware
interfaces
What is a bus? CORRECT ANSWERS set of wires with protocols like IDE disk
controllers
What is a daisy chain? CORRECT ANSWERS when you take different peripheral
devices and connect them to each other. like disk drives
What are the methods for I/O to talk to PC (3)? CORRECT ANSWERS polling - cpu
checks the device periodically
interrupts - peripheral sends a signal to be serviced
DMA - controller can access the memory without using the CPU
What are the 3 blocking options for the I/O? CORRECT ANSWERS Blocking I/O - when
I/O request, process goes to waiting queue
Non-blocking I/O - process is not blocked, and continues
Asynchronous I/O - process continues other tasks and starts back up after I/O is done.
, What is the buffer? CORRECT ANSWERS memory storage which is used to store
temporary data while it travels form one place to a different one.
What are two benefits of buffering? CORRECT ANSWERS allows for different speeds
in devices
makes transfer much smaller
What are the 3 types of buffers? CORRECT ANSWERS single buffer
double buffer
circular buffer - more than one buffer, but oldest data is overwritten
What does disk management include? CORRECT ANSWERS scheduling
buffering
swap space management
What are some attributes of a disk? (3) CORRECT ANSWERS large logical array of
blocks
512 bytes per block often
blocks are separated to sectors
Why is mapping logical to physical so hard for disks? CORRECT ANSWERS
conversion is hard - there could be defective sectors or sectors on a track that are not
consistent.
What is access time? CORRECT ANSWERS total time to fetch the data. It includes:
seek time - time for disk arm to move to cylinder
rotational latency - time for disk arm to get to the right sector
What is disk scheduling? CORRECT ANSWERS a thing the Os manages - this defines
how files are transferred from the disk
What are 6 disk scheduling algorithms? CORRECT ANSWERS First come first served
shortest seek time first
scan
