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Chapter 1 Flashcards

1
Q

What is OS basic

A

A large program

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2
Q

What does OS manage

A

Computer hardware resources, decides between conflicting requests for efficient and fair resource use

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3
Q

What kind of program is OS

A

Control

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4
Q

What is relationship of OS between user of computer and computer hardware

A

Intermediary

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5
Q

Why does OS control execution of programs?

A

To prevent errors and improper use of the computer

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6
Q

What does CPU repeat?

A

Cycle of fetching and executing low level machine instructions

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7
Q

OS goals for user

A

Execute user programs and make it easy and convenient

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8
Q

OS goals system/Hardware

A

Manage resources and use computer hardware efficiently

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9
Q

OS Abstraction

A

The act of removing unimportant details or attributes of objects in order to construct more general and less complex objects

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10
Q

OS Virtualization

A

The act of creating the illusion of having one or more objects with more desirable characteristics than the real object.

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11
Q

How does OS use abstraction?

A

Multiple operations at one level are combined into a single operation at a higher level, making it easier to use

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12
Q

How does OS use virtualization?

A

Create virtual CPUs, memory, I/O devices

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13
Q

Batch Processing

A

Method of running software programs(jobs) in batches automatically with no user interaction required

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14
Q

4 Major OS components

A
  1. Processes and Threads
  2. CPU Scheduling
  3. I/O Management
  4. Memory Management
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15
Q

Multiprogramming

A

Technique that keeps several programs active in memory and switches execution among the different programs to maximize the use of the CPU and other resources

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16
Q

Multiprogramming example

A

When a program enters IO phase then another program can utilize the CPU

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17
Q

Time-sharing (multi-tasking)

A

Extension of multiprogramming where the CPU switches jobs so frequently that users can interact with each job while it is running

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18
Q

What does time-sharing create

A

interactive computing

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19
Q

Time-sharing employs concept of

A

Virtualization by creating illusion of having a separate virtual CPU for each computation

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20
Q

Can abstraction be used without virtualization

A

Yes

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21
Q

Can virtualization be used without abstraction

A

No

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22
Q

Can abstraction and virtualization be used together

A

Yes

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23
Q

Process

A

Program in execution

24
Q

Multitasking gives the _ of _ on one cpu

A

Illusion of parallel processing

25
Q

The OS creates and deletes

A

Processes and threads

26
Q

The OS suspends and resumes

A

Processes and threads

27
Q

The OS schedules

A

Processes and threads

28
Q

The OS provides mechanisms for 3

A

Process Synchronization
Interprocess communication
Deadlock Handling

29
Q

I/O management synchronous

A

Control returns to the user program only upon I/O completion

Wait loop until next interrupt

30
Q

I/O management asynchronous

A

Control returns to user program without waiting for I/O completion
Does this through signal or callback

31
Q

OS 5 design approaches

A

Simple, Layered, Microkernels, Modular, Hybrid

32
Q

Simple Structure

A

No defined layers or modules, starts small and grows in complexity over time

33
Q

Monolithic operating system

A

Design where entire operating system is implemented as a single large program running in a single address space (kernel mode)

34
Q

Layered approach

A

The OS is divided into a series of hierarchical layers, each building on the lower layers, with each layer interacting with only the one directly beneath it

35
Q

Single Layered

A

Enormous amount of functionality crammed into the kernel, no encapsulation

36
Q

Full layered approach

A

The OS is divided into a number of layers, each built on top of lower layers

37
Q

Layered approach advantage

A

Layers can be debugged and replaced independently without bothering the other layers above or below

38
Q

Layered approach cons

A

Appropriately defining the various layers
More overhead

39
Q

Microkernels

A

Reduces the size of the kernel to include only essential OS functions

40
Q

Microkernels idea

A

Minimize the kernel by moving as much functionality as possible from the kernel into user space

41
Q

Microkernel pros

A

Easier to extend, more portable, and more reliable

42
Q

Microkernel cons

A

Performance overhead due to frequent communication between user space and kernel,
Not always realistic, some functions must remain in kernel space

43
Q

Modular

A

A kernel design in which the OS is built from separate modules all within kernel

44
Q

Kernel

A

The minimal set of functions necessary to manage the system resources safely and efficiently.

45
Q

Privileged Instruction

A

Performs critical operations that access I/O devices and the CPU’s status and control registers

46
Q

Who is allowed to use privileged instructions

A

Only OS kernel

47
Q

Kernel Mode

A

CPU state where both privileged and nonprivileged instructions may be used

48
Q

User Mode

A

CPU state where only nonprivileged instructions may be used

49
Q

Any attempt to use privileged instruction in user mode automatically

A

transfers control to kernel mode

50
Q

OS Shell

A

Command interpreter that accepts and interprets textual commands issued by the user via a keyboard

51
Q

System Call

A

A request from an application for an OS service

52
Q

Supervisor call (kernel call)

A

privileged instruction that automatically transfers execution control to a well defined location in the OS kernel

53
Q

Interrupt

A

An event that diverts the current execution of a program to a predefined location in the kernel in order to respond to an event

54
Q

Two popular uses of interrupt

A

Signal to OS completion of IO event
Implement time sharing by periodically switching the PCU among multiple concurrent computations

55
Q

Trap

A

Interrupt triggered by currently executing instruction

56
Q
A

450 (7 decks)

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