Operating Systems: Understanding the Role, Importance and Functionality, Slides of Computer Science

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Operating Systems

2

What is an Operating System?

4

This Course

Bus

Processes, threads, scheduling

Memory management

I/O Management

File Systems Monitor

5

Why care about OS? (1)

You, the CS major

• Most critical software in a computer.
• OS performance influences the performance of

all software on a computer

• How to extract the best performance out of an OS?
• How to work around design flaws? Write software

that takes advantage of the design of the OS

7

Why care about OS? (3)

You, the good programmer

• If you’re going to be a software engineer then

you’ll need to understand the environment

offered by your OS :

• What abstractions does the OS provide? E.g., the OS may (or may not) provide illusions such as infinite number of CPUs, infinite memory, single worldwide computing, etc.
• What system design trade-offs have been made? E.g., what functionality has been put in hardware? What trade-offs have been made between simplicity and performance, putting functionality in hardware vs. software, etc?
• Operating system design and implementation combine many different areas of computer science – languages, hardware, data structures, and algorithms.

Why care about OS (4)

You, the grown-up

10

Class Workload

• Jeopardy games/quizzes every class (10%)
• Problem assignments every chapter (12, 25%)
• 2 programming projects (due weeks 7/13, 35%)
• 3 focused tests during the semester, optional

cumulative final (30%)

Why is this Class Difficult?

• An OS is a very complex software system
  • Rich basic concepts
  • Hundreds of thousands, millions lines of code
• Builds on previous knowledge
  • Computer organization
  • Programming (especially in C)
  • Data structures
  • Algorithms

Class Policies

• Attendance: meaningful participation rewarded
• Missed exams
  • One: final exam score will replace it
  • More: final exam score will replace it only with documented excuse
• Late submissions:
  • Assignments: not considered
  • Projects: 15% penalty per late day
• Academic integrity:
  • Plagiarism is a very serious offense
  • Unlike in the past, it earns an FF in this course

Plagiarism and Cheating

• Please read Academic Integrity chapter from UG Catalog
• Demeaning for you, your colleagues, the department. Huge time

and emotional waster for you, the instructor, TAs and the entire class.

• To prevent falling into temptation:
  • C tutorials to refresh your memory
  • TA and instructor’s help. Start using it this week!
  • Projects split into one-week components (optional to submit weekly work; earns you extra credit for good time management skills)
  • Keep your life load manageable: No, you absolutely cannot pass K (9) credits this semester with a (full time) job (and free time!) Docsity.com^14

Chapter 1

Computer System

Overview Seventh Edition By William Stallings

Operating

Systems:

Internals

and

Design

Principles

Basic

Elements of a

Computer

Basic Instruction Cycle

Instruction Fetch

and Execute

• The processor fetches the instruction from memory

into Instruction Register (IR)

• Program counter (PC) holds address of the

instruction to be fetched next

• PC is incremented after each fetch
• Processor interprets the instruction and performs

required action:

• Processor-memory
• Processor-I/O
• Data processing
• Control