Questions and Answers of Computer Architecture

Many computer manufacturers now include tools or simulators that allow you to measure the instruction set usage of a user program. Among the methods in use are machine simulation, hardware supported
Compiler optimizations may result in improvements to code size and/or performance. Consider one or more of the benchmark programs from the SPEC CPU2006 suite. Use a processor available to you and the
Can you think of a way to test some of the characteristics of an instruction cache using a program? Hint: The compiler may generate a large number of non obvious instructions from a piece of code.
With software prefetching it is important to be careful to have the prefetches occur in time for use but also to minimize the number of outstanding prefetches to live within the capabilities of the
Consider a CPU that implements a single instruction fetch–decode–execute–write back pipeline for scalar processing. The execution unit of this pipeline assumes that the execution stage requires
Using the same notation as in Exercise 5.23, multiply the following numbers. Present your answer in standard decimal notation.a.0545250004822200b.9465000094450000Data from Exercise 5.23The following
For the format used in Exercise 5.19, what decimal number is represented by each of the following numbers in floating point format?a. C2F0000016b. 3C54000016Data from Exercise 5.19Convert the
If you have access to two or more command line interface shells, such as Windows and Linux bash or Linux bash and tcsh, compare the major commands that are available on each. Note the similarities
Describe, in step-by-step form, the procedure that the operating system would use to switch from one user to another in a multi-user time sharing system.
What values would you expect to find in the process state entry in a process control block? What purpose is served by the program counter and register save areas in a process control block? (Note
Discuss the steps that take place when a process is moved(a) From ready state to running state.(b) From running state to blocked state.(c) From running state to ready state.(d) From blocked state to
Why is there no path on the process diagram from blocked state to running state?
Describe what occurs when a user types a keystroke on a terminal connected to a multitasking system. Does the system respond differently for a preemptive or non-preemptive system? Why or why not? If
The multilevel feedback queue scheduling method looks like FIFO at the upper levels and like round robin at the lowest level, yet it frequently behaves better than either in terms of the performance
Discuss the shortest-job-first scheduling method in terms of the various objectives given in the text.
What is the risk that can result from the mixed non-preemptive–preemptive scheduling system taken by Linux, as discussed in the text?
A VSOS (very simple operating system) uses a very simple approach to scheduling. Scheduling is done on a straight round-robin basis, where each job is given a time quantum sufficient to complete very
Earlier versions of Windows used an essentially non-preemptive dispatching technique that Microsoft called “cooperative multitasking”. In cooperative multitasking, each program was expected to
In the memory management schemes used in earlier operating systems, it was necessary to modify the addresses of most programs when they were loaded into memory because they were usually not loaded
Discuss the impact of virtual storage on the design of an operating system. Consider the tasks that must be performed, the various methods of performing those tasks, and the resulting effect on
There are a number of different factors, both hardware and OS software, that affect the operating speed of a virtual storage system. Explain carefully each of the factors and its resulting impact on
Create a page table that meets the translation requirements of Figure 18E.1. Assume a page size of 10.Figure 18E.1 Program 80 100 130 150 310 200 Logical 410 450 memory 500 500 Physical memory
Explain why the installation of additional physical memory in a virtual memory system often results in substantial improvement in overall system performance.
Develop an example that explains thrashing clearly.
What kind of fragmentation would you find in virtual storage? Is this a serious problem? Justify your answer. Discuss the relationship between fragmentation and page size.
Explain why page sharing can reduce the number of page faults that occur in a virtual storage system.
The manual for an old operating system pointed out that the number of concurrent users on the system can be increased if the users are sharing programs, such as editors, mail readers, or compilers.
Explain deadlocking.
The CPU scheduling algorithm (in UNIX) is a simple priority algorithm. The priority for a process is computed as the ratio of the CPU time actually used by the process to the real time that has
Explain the working set concept. What is the relationship between the working set concept and the principle of locality?
Why is the working set concept much more effective if it is implemented dynamically, that is, recalculated while a process is executing?
What are the differences, trade-offs, advantages, and disadvantages between an OS that implements deadlock prevention versus deadlock avoidance versus deadlock detection and recovery?
An operating system designer has proposed using inverted page tables for each process instead of conventional page tables as the lookup tables for each memory reference. Since there are always fewer
Figure 18E.2 shows that, for a given process, the page fault rate in a virtual storage system increases as the page size is increased and then decreases to 0 as the page size approaches P, the size
Assume that you have a program to run on a Little Man-type computer that provides virtual storage paging. Each page holds ten locations (in other words, one digit). The system can support up to one
What is a real-time system? Discuss the impact of a real-time system on the design of the operating systems, paying particular note to the various components and algorithms to be used.
Consider the operation of a jukebox. Each table has a jukebox terminal where customers can feed coins to play songs (50 cents apiece, three for a dollar). Prior to the iPod era, the queue to hear
Tanenbaum notes that the problem of scheduling an elevator in a tall building is similar to that of scheduling a disk arm. Requests come in continuously, calling the elevator to floors at random. One
Discuss possible tape scheduling algorithms for a tape controller. Assume that files are stored contiguously on tape. What effect would non-contiguous, linked files have on your algorithm?
You may have noticed a number of similarities between virtual storage paging and cache memory paging. One major difference, of course, is that main memory is much faster than disk access.Consider the
The designer of a new operating system to be used especially for real-time applications has proposed the use of virtual storage memory management so that the system can handle programs too large to
Discuss the various trade-offs and decisions involved in task dispatching and the options and methods used for implementing those trade-offs and decisions.
A system status report for a virtual storage operating system shows that between 2 p.m. and 4 p.m. CPU usage and I/O usage both climbed steadily. At 4 p.m., the I/O usage reached 100 percent, but
Discuss the network features and services provided in an operating system. Which services are mandatory? Why?
Explain the bootstrap procedure for a diskless workstation.
Consider the operation of an OS dispatcher on a computer with multiple cores operating under symmetric multiprocessing. Assuming that there are more processes being executed than there are cores, the
List and explain some definite advantages to the use of a command line interface over other types of interfaces. Do the same for a graphical user interface. Do the same for aWeb-based interface. What
Discuss the advantages and disadvantages of providing the user interface as a separate shell, rather than as an integral part of the operating system.
Consider the major commands in a command line interface system such as the Linux bash shell. Explain how each task would be performed on a graphical user interface system such as Windows or the
There are some capabilities that are easy to achieve with a GUI, but much more difficult with a CLI. Describe a few of these capabilities.
Explain piping. What additional capability does piping add to a command language?
Explain the concept of redirection. Illustrate your answer with an example of a situation where redirection would be useful.
What purpose do arguments serve in a batch file or shell script?
Identify the name and purpose of each of the components of the GUI that you use.
Describe the difficulties that exist in providing a GUI at a location remote from the computer that is creating the display. Describe the methods used by X Window to partially overcome these
Discuss the advantages that result from the client–server architecture of the X Window system.
When people describe client–server architecture, they are usually referring to a system in which a large server is serving a client on a PC. With XWindow, the reverse is frequently the case.
The designers of the UNIX operating system described the ideal shell command language as one that is made up of a large set of simple commands, each designed to perform one specialized task well.
If you could design a “wild card” system with features beyond those normally provided in a CLI, what features would you add?
Suppose that you are designing an app for a mobile device, such as an iPhone or Android device. Name several services that you would expect to find in the operating system API to assist you with your
You have noticed that loading the programs from your hard disk seems to take longer than it used to. A friend suggests copying the files from your disk, one at a time, to a different device, and back
Explain why a MOVE operation from one device to another requires manipulation of the file itself, whereas a MOVE operation from one place to another on the same device involves manipulation only of
In many systems, the operations that work on a file as a whole are made up by combining the operations that manipulate the internal file data. Explain how you would copy a file from one location to
From a Windows command line prompt, do a DIR command. Carefully note how much space remains on your disk. Now open up NOTEPAD, and create a new file containing just a period with a carriage return.
List a number of types of files that you would expect to be accessed sequentially. Do the same for files that you would expect would require random access.
Explain the trade-offs between contiguous, non-contiguous linked, and non-contiguous indexed file allocation. In particular, note the effect on sequential and random access methods.
Assume a UNIX i-node requires a block of 60 bytes. How many disk blocks can be accessed using just direct, single, and double indirect indexing, as shown in Figure 17.9?Figure 17.9 file file
What are the advantages of partitioning a disk, rather than using the entire disk as one partition?
What does it mean to mount a disk?
What role does a path serve?
Explain the specific file privileges for each file in Figure 17.21. Who is the owner of these files? What is the name of the group that has access to these files?Figure 17.21 $1s -1F 1 iengland
The access control list for a file specifies which users can access that file, and how. Some researchers have indicated that an attractive alternative would be a user control list, which would
a. Disk caching is a technique that is used to speed up disk access by holding blocks of disk in memory. Discuss strategies that could be used to improve system performance with disk caching.b. The
Consider a file that has just grown beyond its present space on disk. Describe what steps will be taken next for a contiguous file, for a linked non-contiguous file, and for an indexed file.
One approach to operating system design is to provide as small a kernel as possible and to make all other modules optional. What are the minimum services that must be provided in such a miniature
Write a Little Man bootstrap loader that will reside permanently in high memory for the Little Man Computer. The reset button will automatically cause the Little Man to start executing the first
Windows hides most of its configuration in a binary file called the registry. Special Windows tools must be used to read and modify the registry. What are the advantages and disadvantages of this
Based on the system status report shown in Figure 15.5, describe some of the ways in which the system could be tailored, and explain how the various items in the report would influence your tailoring
What are the conditions and restrictions that you would want to impose on a multitasking system that is being used with real-time processes?
What operating system functions would you expect to find in the computer that is built in to control your automobile, and which functions would be omitted? Justify your answer.
Clearly explain the differences between multi-programming, multi-user, and multiprocessing.
a. Of what use is the list of active processes shown in Figure 15.5? What changes might a system administrator make in the system on the basis of this information?b. What does the average number of
What is an interrupt vector?
Early versions of Windows did not support true preemptive multitasking. Instead, the designers of Windows provided something they called “cooperative multitasking” in which each program was
Discuss the similarities and differences between memory management fragmentation and disk fragmentation.
Nearly every operating system separates the file system from the I/O services. What is the advantage in doing so?
What is the difference between the logical description of a file and the physical description?
An operating system is described as an event-driven program. What is meant by event driven? Explain how the dispatching operation fits this description.
Describe the two methods that are used to provide concurrent operation of multiple processes on a single CPU. What are the advantages of each method? What is the advantage of providing concurrent
You are probably familiar with the standard Windows interface. Suppose you could replace the Windows shell with a different interface shell. What might be the advantages and disadvantages of
What are the limitations of providing a BIOS in ROM?
Concurrency, of course, is a requirement for modern operating systems. What are the major challenges that an OS designer faces in supporting efficient concurrency that she would not face if the
For each of the most popular commands in Windows (or Linux if you prefer), identify the type of operating system service that is being provided, and identify the basic module or modules that are
What are the specific limitations of a computer system that provides no operating system? What must be done to load and execute programs?
a. What is the binary sequence represented by the 4B/5B encoded sequence11110011111101111110?b. What is the binary sequence represented by the 4B/5B encoded sequence10101010101010101011?
The Little Prince Computer (LPC) is a mutant variation on the LMC. (The LPC is so named because the differences are a royal pain.) The LPC has one additional instruction. The extra instruction
a. Consider a CPU with two parallel integer execution units. An addition instruction requires 2 clock pulses to complete execution, and a multiplication requires 15 clock pulses. Now assume the
Write a program in your favorite language that will convert all ASCII uppercase and lowercase letters to EBCDIC code. For an additional challenge, also convert the punctuation symbols, indicating
Approximately how many pages of pure 16-bit Unicode text can a 650MB CD-ROM hold?
What are the 16-bit 1’s and 2’s complements of the following binary numbers?a. 10000b. 100111100001001c. 0100111000100100

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