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HW & Systems: Operating Systems IS 101Y/CMSC 101 Computational Thinking and Design Tuesday, October 22, 2013 Carolyn Seaman University of Maryland, Baltimore County. Today. Operating Systems Midterm Guest lecture about Computer Engineering from Dr. LaBerge Sit with your teams

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Today

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  1. HW & Systems:Operating SystemsIS 101Y/CMSC 101Computational Thinking and DesignTuesday, October 22, 2013Carolyn SeamanUniversity of Maryland, Baltimore County

  2. Today • Operating Systems • Midterm • Guest lecture about Computer Engineering from Dr. LaBerge • Sit with your teams • No need for laptops to be open • Avoid the back middle section

  3. Wherefore OS? • A “naked machine”has no tools or programs to help the user • Write instructions in binary • Write data in binary • Load instructions into memory one cell at a time • Initiate program run • Too difficult for humans to do • We must build an interface to hide the details and make the computer easier to build • The OS is an abstraction of the machine that keeps users and programmers from having to think about the low-level hardware details

  4. Virtual Machine (abstraction!) Naked machine: • Write program in binary • Load instructions one-by-one into memory • Insert start into memory address 0 and push “go” button • Read results from memory one-by-one, in binary Virtual machine: • Write program using text editor in high-level language • Save program to folder • Use translator to convert to binary • Use scheduler to load and run • Use I/O system to print results

  5. UnQuiz • What is the kernel? What are its main functions? • What is the difference between a program, a process, and a thread? • What is multitasking? • When does the kernel interrupt a running process? • What is a context switch?

  6. UnQuiz Part Two • What are some possible process scheduling policies? • What do these different ways of measuring CPU efficiency mean? • CPU utilization • Average latency • Throughput • Fairness • What is virtual memory?

  7. Deadlock • Safe use of resources: ensure that computer doesn’t get stuck in deadlock • Multiple programs requesting access to resources • Deadlock occurs when all programs have some resources, and are waiting for resources held by others • Deadlock prevention: if you can’t get all resources, release all you have and try again later • Deadlock recovery: if no acknowledgement, send message again

  8. Midterm Review

  9. Guest LectureDr. Chuck LaBergeComputer Engineering

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