Introduction

Question 1

Operating System

Answer 1

Intermediary between user and computer

Question 2

Goal of OS

Answer 2

Make hardware easy & efficient to use

Question 3

2 OS Features

Answer 3

Resource allocate, control program

Question 4

Resource allocator

Answer 4

decides between conflicting requests for efficient and fair resource use

Question 5

control program

Answer 5

controls execution of programs to prevent errors and improper use of computer

Question 6

Kernel

Answer 6

running the whole time

Question 7

Bootstrap program

Answer 7

Loaded at power up (Firmware) handles kernel startup

Question 8

I/O and CPU

Answer 8

Concurrently execute

Question 9

How do device controllers end opperation

Answer 9

Cause an interrupt

Question 10

Trap

Answer 10

software generated interrupt caused by error or user request

Question 11

Interrupt vector

Answer 11

Contains addresses of all service routines

Question 12

How does OS determine interrupt type?

Answer 12

Polling or vectored interrupt system

Question 13

System Call

Answer 13

Request to the operating system to allow user to wait for I/O completion

Question 14

Device status table

Answer 14

contains entry for each I/O device indicating its type, address, and state
◦ OS indexes into the I/O device table to determine device status and to modify the table entry to include
interrupt

Question 15

Job Scheduling

Answer 15

When OS has to wait (ex: for I/O), switches to another job

Question 16

Timesharing

Answer 16

CPU switches jobs so frequently that each user can interact with each job while its running

Question 17

Dual mode

Answer 17

User mode and kernal mode with separate priviledges

Question 18

Protection

Answer 18

mechanism for controlling access of processes or users to resources defined by the OS

Question 19

User ids

Answer 19

determine which users and groups of users have which privileges