Lecture 18: Operating Systems Intro to IT COSC1078 Introduction to Information Technology Lecture 18 Operating Systems James Harland [email protected]
Lecture 18: Operating Systems Intro to IT COSC1078 Introduction to Information Technology Lecture 18 Operating Systems James Harland [email protected].
Jan 13, 2016
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Lecture 18: Operating Systems Intro to IT
COSC1078 Introduction to Information Technology
Lecture 18
Operating SystemsJames Harland
Lecture 18: Operating Systems Intro to IT
Introduction to IT
1-4 Introduction, Images, Audio, Video
5-6 Computer Fundamentals Assignment 1, WebLearn Test 1
7 Review
8 Operating Systems WebLearn Test 2
9 Operating Systems Assignment 2
10 Internet
11 Internet Security WebLearn Test 3
12 Future of IT Assignment 3, Peer and Self Assessment
Lecture 18: Operating Systems Intro to IT
Overview
Questions?
Assignment 2
Operating Systems
Questions?
Lecture 18: Operating Systems Intro to IT
Assignment 2
Now in the Learning Hub Assumes you are using Audacity If not, please see me asap Seems a lot, but shouldn’t be too hard once you
have Audacity and your files CD task requires CD reading software
Windows: ImgBurn www.imgburn.com
Mac: Burn, Toast
Linux: ImgBurn via Wine, or K3B, Brasero, Nero, …
Lecture 18: Operating Systems Intro to IT
Processes
Lecture 18: Operating Systems Intro to IT
Processes
A program is a static set of instructions
A processes is the execution of a program, which changes state over time.
Lecture 18: Operating Systems Intro to IT
Processes Switching
Ready
Ready
Waiting
Scheduler maintains process table
Lecture 18: Operating Systems Intro to IT
Processes Switching
Lecture 18: Operating Systems Intro to IT
Interrupts
Signals to the CPU Often generated by timing circuits CPU reacts by jumping to appropriate memory location Dispatcher
selects a ready process resets timing circuit starts process
CPUs often designed to switch process states efficiently
Lecture 18: Operating Systems Intro to IT
Interrupts
Provide mechanism to switch processes
CPU doesn’t have to wait for I/O transfers
Switching leads to faster throughput
`Save document’ means CPU does something else while the save takes place
Lecture 18: Operating Systems Intro to IT
Memory Management
Memory Disk
Mine!
Mine!
Mine!
STOP IT!
Lecture 18: Operating Systems Intro to IT
Virtual Memory
What if memory requirements exceed memory size?
Pretend we have more!
Shuffle required parts (pages) between disk and memory
Not every memory cell is needed all the time…
Lecture 18: Operating Systems Intro to IT
Virtual Memory
Virtual Memory
DiskPhysical MemoryP
rocesssor
Lecture 18: Operating Systems Intro to IT
Co-ordination and locking
MINE!
MINE!
MINE!
Works fine for one resource …
Lecture 18: Operating Systems Intro to IT
Deadlock
Deadlock: neither can get both resources
Lecture 18: Operating Systems Intro to IT
Deadlock requirements
Deadlock requires:
1.Competition for nonshareable resources2.Processes request multiple resources sequentially3.Resources cannot be forcibly retrieved
Avoid deadlock by preventing 1 or 2Detect and correct deadlock by falsifying 3
Lecture 18: Operating Systems Intro to IT
Deadlock avoidance
Spooling makes nonshareable resources look like shareable ones …
Lecture 18: Operating Systems Intro to IT
Operating Systems
Highly complex software systems
30-40 million lines of code
Lots of processes associated with them
Probably most sophisticated software ever written
Not many of them around …
Lecture 18: Operating Systems Intro to IT
Operating Systems
Lecture 18: Operating Systems Intro to IT
Conclusion
Work on Assignment 2
Web Quizzes and Web Test 2
Finish reading book!
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