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CGS 3763 Operating Systems Concepts Spring 2013. Dan C. Marinescu Office: HEC 304 Office hours: M- Wd 11:30 - 12:30 A M. Last time: Networking concepts Today: Solutions to HW1 Student questions for week 4 More network concepts Client-server systems
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CGS 3763 Operating Systems Concepts Spring 2013 Dan C. Marinescu Office: HEC 304 Office hours: M-Wd 11:30 - 12:30 AM
Last time: Networking concepts Today: Solutions to HW1 Student questions for week 4 More network concepts Client-server systems Remote procedure call Next time Shared memory systems Pipes Reading assignments Chapters 3 and 4 of the textbook Chapters 3 and 4 textbook slides Lecture 14 – Friday, February 8, 2013 Lecture 13
Solutions to HW1 • 1.2 What are the main differences between an OS for a mainframe and one for a PC? • Mainframe: a. more sophisticated resource management policies; b. additional functionality, e.g., it has to support accounting; c. enhanced security. • 1.3 What are the four steps involved in the execution of an instruction on a stored-program computer? • Instruction fetch from the address pointed at by the PC (Program Counter) into the IR (Instruction Register). • Instruction decode. • Instruction execution. • Write back the results Lecture 13
Solutions to HW1 3 Several users sharea system in multiprogramming and time-sharing environments and this can result in security problems: (a) List two such problems; (b) Can we ensure the same level of security in a time-shared system as in a dedicated machine. Explain your answer. a. Security and privacy; unpredictable execution time. b. Probably not, since any protection scheme devised by humans can inevitably be broken by a human, and the more complex the scheme, the more difficult it is to feel confident of its correct implementation. Lecture 13
Solutions to HW1 • 1.14What resources must be managed carefully in the following settings: (a) Mainframe of minicomputer systems; (b) Workstations connected to servers; (c) Handheld computers. • Mainframes: memory, CPU, primary and secondary storage, network. • Workstations: memory,CPU, network • Handheld computers: power consumption, memory resources, display, RF (Radio Frequency) subsystem for wireless communication. • 1.15 Under what circumstances would a user be better off using a time-sharing system rather than a PC or a single-user system? • (a) When the amount of computing resources (CPU cycles, primary and secondary storage) is considerable. • (b) When the problems requires a collaborative effort of several users. Lecture 13
HW1 solutions • 1.21 How are network computers different from traditional PCs? Describe some usage scenarios in which it is advantageous to use network computers. • A network computer has limited resources and relies on systems accessible via the Internet for data storage and for computing; its price is low. The OS of a network computer supports a small number of functions. Chromebook is an example of a network computer see • http://www.google.com/intl/en/chrome/devices/#foreveryone-promo-samsung • Typical usage scenario: Web access, Email access. Lecture 13
Student questions • Jan 30th Wednesday: • More on the fork() or exec() commands. • Better explanation of pipelining and what it is. • Where does the PCB come into play? • Explain further the concept of an interrupt. What is an interrupt vector? • What determines which process has more priority over another process? • What is the purpose of the program counter? Why do we need to know this? Lecture 13
Student questions • Feb 1st Friday: • What is the main difference between independent and cooperating within a system? • RISC/CISC Architecture: what exactly are these two architectures? What is an example of CISC machine and where are they used? What is the advantage or disadvantage of these versus the standard RISC? • Further explain branch execution. • Explain in greater detail of a process creation and what it is used for? • What is a Producer-Consumer Problem? What is a flag/condition code, where does it come in place? • What are the major differences between layered and modular systems? Lecture 13
Peer-to-peer communication Lecture 13
Local and wide area networks Lecture 13
Encapsulation/ de-capsulation Lecture 13
IPV4 and IPv6 datagrams Lecture 13
Multiplexing, de-multiplexing Lecture 13