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Chapter 2
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Chapter 2
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1
Question
What is the primary role of an operating system (OS)?
Answer
OS is a program interface between applications and hardware, controls application program execution.
2
Question
What are the three main objectives of an operating system?
Answer
Convenience, efficiency, ability to evolve.
3
Question
List some functions of an operating system related to program development and execution.
Answer
Program development, program execution, access IO devices.
4
Question
What is the role of an operating system in managing resources in a computer system?
Answer
The OS is responsible for managing the resources for the movement, storage, and processing of data.
5
Question
What is a function in terms of computer software?
Answer
A program or suite of programs executed by the processor that frequently relinquishes control and depends on the processor to allow it to regain control.
6
Question
What are some reasons for the evolution of operating systems over time?
Answer
Hardware upgrades, new types of hardware, new services, and fixes are some reasons for the evolution of operating systems.
7
Question
What are the stages in the evolution of operating systems?
Answer
The stages include serial processing, simple batch systems, multiprogrammed batch systems, and time-sharing systems.
8
Question
Describe the characteristics of serial processing in the context of operating systems.
Answer
In serial processing, computers ran without an operating system, programmers interacted directly with the hardware, and users accessed the computer in series.
9
Question
What were the problems associated with serial processing in early computers?
Answer
Problems included scheduling difficulties, where time allocations could run short or long resulting in wasted computer time, and setup time spent on setting up programs to run.
10
Question
What were the characteristics of simple batch systems in the evolution of operating systems?
Answer
In simple batch systems, computers were expensive, users no longer had direct access to the processor, and jobs were submitted to a computer operator who batched them together.
11
Question
What was the role of the monitor in a simple batch system?
Answer
The monitor in a simple batch system maximized processor utilization by queuing jobs and routing them to the processor when available.
12
Question
What is the purpose of setting up Simple Batch Systems?
Answer
To maximize processor utilization and save costs on early expensive computers.
13
Question
In Simple Batch Systems, who monitors user activities?
Answer
The computer operator, as users no longer have direct access to the processor.
14
Question
What happens to a job after it is submitted in a Simple Batch System?
Answer
The job is batched together with other jobs by the computer operator and placed on an input device.
15
Question
What occurs when a program finishes execution in a Simple Batch System?
Answer
The program branches back to the monitor for further monitoring and control.
16
Question
What is a Resident Monitor responsible for?
Answer
Controlling the sequence of events and always staying in memory
17
Question
What does the Monitor do after reading in a job?
Answer
It gives control to the job
18
Question
What happens after a job returns control to the Monitor?
Answer
The processor executes instructions from the memory containing the monitor
19
Question
What happens when the processor encounters an ending or error condition in a user program?
Answer
Control is passed back to the job
20
Question
When control is returned to the monitor, what is the processor doing?
Answer
Fetching and executing instructions from the monitor program
21
Question
What is JCL (Job Control Language)?
Answer
A special type of programming language used to provide instructions to the monitor
22
Question
What is the purpose of Memory Protection for the monitor?
Answer
To prevent a job from monopolizing the system and ensure user program execution does not alter the monitor's memory area
23
Question
What can only be executed by the monitor?
Answer
Timer
24
Question
What do Privileged instructions allow the OS to do?
Answer
Have more flexibility in controlling user programs
25
Question
What are the two Modes of Operation?
Answer
User Mode and Kernel Mode
26
Question
In which mode does a user program execute?
Answer
User Mode
27
Question
What restrictions are there in User Mode?
Answer
Certain areas of memory are protected from user access and certain instructions may not be executed
28
Question
In which mode does the monitor execute?
Answer
Kernel Mode
29
Question
What is allowed in Kernel Mode?
Answer
Execution of privileged instructions and accessing protected areas of memory
30
Question
What is User Mode in operating systems?
Answer
User program executes in user mode, certain areas of memory are protected from user access, and certain instructions may not be executed.