Operating Systems

Question 1

What is an operating system?

Answer 1

An operating system is a program that manages the computer hardware. It also provides a basis for application programs and acts as an intermediary between the computer user and the computer hardware.

Question 2

What are the 4 components of a computer system?

Answer 2

The 4 components are the hardware, the operating system, the application programs, and the users.

Question 3

What is the initial program that a computer runs?

Answer 3

The bootstrap program

Question 4

Why are static programs stored in read-only memory?

Answer 4

Because read-only memory cannot be changed.

Question 5

Why aren’t programs and data aren’t stored in main memory?

Answer 5

Because main memory is too small to store all needed programs and data permanently and because main memory is volatile storage (it will lose all its contents when power is turned off).

Question 6

What is the storage device hierarchy?

Answer 6

registers

Question 7

What are the 3 main advantages of multiprocessor systems?

Answer 7

Increased throughput, economy of scale, and increased reliability.

Question 8

What is asymmetric multiprocessing?

Answer 8

Asymmetric multiprocessing is when a processor is assigned a separate task.

Question 9

What is symmetric multiprocessing?

Answer 9

Symmetric multiprocessing is when all processors perform the tasks within the operating system.

Question 10

What are blade servers?

Answer 10

When multiple processor boards, I/O boards, and networking boards are placed in the same chassis.

Question 11

Name the 6 types of system calls.

Answer 11

1) process control, 2) file manipulation, 3) device manipulation, 4) information maintenance, 5) communications, and 6) protection

Question 12

What is a process?

Answer 12

A process is a program in execution.

Question 13

Name the 5 states a process can be in.

Answer 13

New = the process is being created. 
Running = instructions are being executed. 
Waiting = the process is waiting for some event to occur (like a I/O completion). 
Ready = the process is waiting to be assigned to a processor. 
Terminated = the process has finished execution.

Question 14

What kind of information does the process control block contain?

Answer 14

The process control block contains information such as process state, program counter, CPU registers, CPU-scheduling info, memory management info, accounting info, and I/O status info.

Question 15

What does the process scheduler do?

Answer 15

The process scheduler selects an available process (possibly from a set of available processes) for program execution on the CPU.

Question 16

What is the difference between the long-term scheduler and the short-term scheduler?

Answer 16

The long-term scheduler (or the job scheduler) selects a process from a mass-storage device and loads them into memory for execution.

The short-term scheduler (CPU scheduler) selects from among the processes that are ready to execute and allocates the CPU to one of them.

Question 17

What is the difference between an I/O-bound process and a CPU-bound process?

Answer 17

An I/O-bound process is one that spends more of its time doing I/O than it spends doing computations.

A CPU-bound process is a process that generates I/O requests infrequently, using more of its time doing computations.

Question 18

What is a medium-term scheduler?

Answer 18

A medium-term scheduler is an intermediate type of scheduler that removes a process from memory and (and from active contention for the CPU), reducing the degree of multiprogramming.

Question 19

What are the 2 fundamental models of interprocess communication (IPC)?

Answer 19

The 2 fundamental models of interprocess communication are 1) shared memory and 2) message passing.

Question 20

What are the four main benefits of multithreaded programming?

Answer 20

The four main benefits are :
1) responsiveness = allows a programming to continue running even if part of it is blocked or performing a lengthy operation.

2) resource sharing = separate processes share resources through shared memory and message passing but threads share memory and the resources of the process by default.
3) economy = since threads share memory and resources by default there is no reason to allocate these things which can be costly.
4) scalability = multithreaded processes can run in tandem with a multiprocessor architecture which increases parallelism.

Question 21

Name five challenges to programming for multicore systems.

Answer 21

1) dividing activities = examining applications to find areas that can be divided into separate, concurrent tasks
2) balance = how to ensure that the divided tasks perform equal work of equal value.
3) data splitting = finding out how to split the data being accessed and manipulated amongst the divided tasks.
4) data dependency = finding out if any of the data being accessed or manipulated by a task depends on other data
5) testing and debugging = finding out how to test all execution paths for the multiple cores.