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Computer systems

Operating systems




GENERAL


Explain the purpose and operation of THREE of the following:   [20 Marks]
  1.   Bootstrap.
  2.   CPU cache.
  3.   File Allocation Table (FAT).
  4.   Spooling.



Operating systems have been used for many years.
  1.   Explain the current meaning of the term Operating System.   [4 Marks]
  2.   Explain how the following have improved the efficiency of computer systems:   [10 Marks]
    1.   Single Stream Batch Processing.
    2.   Multiprogramming.
    3.   Spooling.
  3.   Describe briefly TWO of the following user interfaces:   [6 Marks]
    1.   Job Control Language.
    2.   Command Line.
    3.   Graphical User Interface.



The task of downloading a chosen web page with any embedded files is achieved using standard Internet protocols and additional software. Explain the downloading process with reference to the following terms:   [20 Marks]
  1.   Browser.
  2.   Hyperlink.
  3.   Uniform resource locator (URL).
  4.   Domain name system (DNS).
  5.   IP address.
  6.   Web server.
  7.   Plug-in.
  8.   Html file and tags.


BOOTSTRAP


  1.   Computers start by means of a 'bootstrap' process. For a single user system, such as a typical Personal Computer (PC):
    1.   Describe in detail the start-up process from the execution of the bootstrap until application programs can be run.   [8 marks]
    2.   If the computer failed to start from the main hard disc drive, explain the recovery actions you would take.   [4 marks]
  2.   Memory management is mainly the responsibility of the operating system.
    1.   Explain briefly the likely taks in managing the main memory of any computer.   [5 marks]
    2.   Sketch a memory map of a computer (PC or other) to show how the memory areas might be employed.   [3 marks]



Computers start by means of a 'bootstrap' process. For a single user system, such as a typical Personal Computer (PC):
  1.   Describe in detail the start-up process from the execution of the bootstrap until the operating system takes control.   [8 marks]
  2.   Explain how main memory of 256 Mbytes would be organised and allocated.   [8 marks]
  3.   If the computer failed to start from the main hard disc drive, explain the recovery actions you would take.   [4 marks]



Computers usually start by means of a 'bootstrap' process, although this may fail. In some cases, the operating system can detect and rectify problems on the hard disc drive using a disc utility program such as Chkdsk or Scandisk.
  1.   Describe the steps in a typical bootstrap process for a personal computer (PC) from powering up until the operating system has taken control.   [8 marks]
  2.   If the PC failed to boot from the hard disc, suggest what actions the user could take to start the computer.   [4 marks]
  3.   Explain the actions of a disc utility program, describing the types of problems which can be detected and the remedial actions which can be taken.   [8 marks]



Most computers start by means of a bootstrap process, although this may fail. In some cases, the operating system can detect and rectify problems on the hard disc drive using a disc utility program such as Chkdsk or Scandisk.
  1.   Describe the steps in a typical bootstrap process for a personal computer (PC) from powering up until the operating system has taken control.   [8 marks]
  2.   If the PC failed to boot from the hard disc, suggest what actions the user could take to start the computer.   [4 marks]
  3.   Explain the actions of a disc utility program, describe the types of problems it can detect and the corrections it can make.   [8 marks]


SCHEDULING


Modern operating systems (and the Java Virtual Machine) need to manage the problems of concurrency which can arise during multiprogramming and multitasking.
  1.   Explain the term multiprogramming.   [3 marks]
  2.   Explain how problems of concurrency can arise in multiprogramming; (use a diagram and an example such as printer operation to clarify your description.)   [7 marks]
  3.   Describe TWO possible consequences if concurrency problems are not handled correctly.   [4 marks]
  4.   Describe in detail ONE technique for handling concurrency. Discuss whether your method would be effective both for printer and disc operation.   [6 marks]



Low Level Scheduling is an important function of the operating system (OS). Schedulers incorporate various strategies such as a processor (CPU) fixed time-slice or run-to-completion logic.
  1.   Explain the term Scheduling, including its purpose.   [4 Marks]
  2.   Explain briefly what is meant by an input-output (I-O) bound program, and a processor (CPU) bound program.   [4 Marks]
  3.   Describe briefly the Fixed Time-slice and the Run-to-completion strategies of job scheduling.   [6 Marks]
  4.   For each of the two strategies in c., provide an example to illustrate a possible scheduling problem and suggest a solution.   [6 Marks]



Scheduling is one function of the operating system.
  1.   Explain the term Scheduling, distinguishing between high level and low level scheduling.   [4 Marks]
  2.   Discuss the overall objectives of any scheduling scheme.   [6 Marks]
  3.   Describe briefly the characteristics of a program which should be considered by the scheduler.   [4 Marks]
  4.   Discuss the main scheduling strategies in use, concentrating on the choice of 'next job to run' and the period of processor time allocated.   [6 Marks]



Polling is one method of transferring data between the peripherals and their processor. Polling is effective for a small number of peripherals; however, as the number and the speed of peripherals increase, polling becomes unsatisfactory and a better method is needed.
  1.   Explain in detail how polling operates in a system which has a small number of peripherals.   [7 Marks]
  2.   With reasons, explain the problems which arise from polling:   [5 Marks]
    1.   As the number of peripherals increases.
    2.   As the speed of peripherals increases.
  3.   Name an alternative method of handling peripheral transfers which improves on polling. Describe the hardware features and software functions needed to support the method. Explain the operation of the method and describe its advantages.   [8 Marks]



Spooling systems are widely available on most computers, often in the form of a 'print manager'.
  1.   Explain the abbreviation 'SPOOL'.   [2 Marks]
  2.   Suggest TWO reasons for using a spooling system.   [4 Marks]
  3.   Describe in detail the components and operation of a typical spooling system used for generating print-out.   [10 Marks]
  4.   Describe briefly FOUR features (refinements or controls) normally available on a modern spooling system.   [4 Marks]


FILE SYSTEM


Operating systems employ a directory structure to help manage their file organisation. The Windows operating system uses a 16-bit or 32-bit File Allocation Table (FAT).
  1.   With the aid of a diagram, explain how the root directory, sub-directories (folders) and files are mapped on the sectors of a disc drive. Show how pointers help to create a tree structure.   [8 marks]
  2.   Describe the two main functions of the FAT, and, with the aid of a diagram, explain how the FAT entries are organised.   [8 marks]
  3.   Explain briefly the implications of choosing between a 16-bit and a 32-bit FAT on a 2 GByte hard disc.   [4 marks]



Operating systems employ a directory structure to help manage their file organisation. The MS-DOS and Windows operating systems have also used either a 16-bit or 32-bit File Allocation Table (FAT).
  1.   With the aid of a diagram, explain how the root directory, sub-directories (folders) and files are mapped on the sectors of a disc drive. Show how pointers help to create a tree structure.   [8 marks]
  2.   Describe the two main functions of the FAT, and, with the aid of a diagram, explain how the FAT entries are organised.   [8 marks]
  3.   Explain briefly why most personal computers were upgraded from a 16-bit and a 32-bit FAT.   [4 marks]



File directory systems are required on disc storage to control the allocation of program and data files. On a particular floppy diskette, having 1440 sectors of 512 bytes, the disc operating system manages a single level directory.
  1.   Describe a suitable structure for the file directory.   [5 Marks]
  2.   Describe the steps in creating a new file on the diskette.   [5 Marks]
  3.   Show how an existing file is accessed.   [3 Marks]
  4.   Suggest one practical difficulty that might arise after prolonged use of the directory system. How might be problem be removed?   [4 Marks]
  5.   Give one reason why the single level file structure might be unsuitable for a large capacity hard disc system.   [3 Marks]



Most hard disc operating systems employ a directory structure to manage their files. The operating system maps the directory structure on the hard disc sectors, often in conjunction with a file allocation table (FAT) or a bitmap.
  1.   With the aid of a diagram, explain how the root directory, sub-directories and files are organised on the sectors of the hard disc.   [8 marks]
  2.   Explain in detail the purpose and operation of the File Allocation Table (or the bitmap).   [6 marks]
  3.   If a file is accidentally deleted, discuss whether it can be recovered from the hard disc using the FAT or bitmap.   [6 marks]