Faculty of Environment and Technology

Transcription

1 Faculty of Environment and Technology Academic Year: 12/13 Examination Period: January Module Leader: Module Code: Title of Module: Craig Duffy UFCEHX-20-2 Computer Networks and Operating Systems Duration of Examination: 2 Hours Instructions to Candidates: Candidates must answer ALL questions from Section A AND ONE question from Section B Materials supplied to the candidate will be: Number of Examination Booklets per Examination 1 Number of sheets of Graph Paper size G3 (Normal) 0 Number of Pre-printed OMR (Multiple Choice Answer Sheet) 0 Additional Instructions to Invigilators: University approved calculators may be used Yes Candidates permitted to keep Examination Question Paper Material supplied by student allowed (must be collected with answer booklet) please specify: Yes No Additional Specialised Material : NONE Treasury tags will be supplied as standard. UFCEHX-20-2 Page 1 of 5

2 SECTION A Attempt all questions in this section. 1) Outline the relationship between the BIOS and operating system in a standard desktop PC. 2) Briefly discuss how semaphores can be used to help control access to critical regions within operating system code. 3) File permissions have frequently been seen as a weak point in UNIX/Linux operating systems. Briefly explain what they are and what their weaknesses are. 4) Provide an outline for a data structure for an operating system process control block. A short comment must identify the purpose of each field in your struct. 5) Briefly outline the pros and cons of using Open Source software within a commercial development. Page 2 of 5

3 SECTION B Answer any one question in this section. 6) GNU/Linux uses both paged and segmented memory in its approach to memory management. i) Show, in the form of a table, the advantages and disadvantages of paged versus segmented memory. (8 Marks) ii) The architecture dependent part of GNU/Linux on the i386 architecture uses paged memory management. Explain, with the aid of diagram (i), how the page table structure is organized. Your answer should include an explanation of the fields in the page table entry. (10 Marks) diagram (i) Page 3 of 5

4 iii) Pages sometimes need to be removed from memory in order to make space for another processes pages. There are a number of different algorithms that could be used, these include the FIFO, modified FIFO and NRU algorithms. Describe how these three work, along with any advantages or disadvantages. (7 Marks) 7) i) Decisions have to be made when partitioning a disk drive prior to installing GNU/Linux. Explain: why you might want to create several partitions. (3 Marks) which parts of the file system might have their own partition. Why you might need a swap partition and what its role is. what might affect your choice of block size when using an ext2 file system. ii) Answer the following with respect to either a) a web server installation or b) a program development platform. When installing GNU/Linux for one of the above you will need to make decisions regarding the disk partioning, file system type, users, software, etc in order to make sure that you have only the required packages and utilities installed. Describe the decisions that you would make for your chosen installation and justify them. (10 marks) 8) Provide secure, reliable access to user data through a file system is a familiar feature of operating systems. Page 4 of 5

5 I) Describe the types in file system interface you would expect to find on a general purpose operating system. Give details of how those interfaces might be used by a programmer. (9 marks) ii) iii) Discuss, using a file system you are familiar with, how file systems map their file system structures onto the various types of storage hardware they are implemented on. (10 marks) The provision of file access control through user and group accounts is mandatory for most modern operating systems. Discuss how this provision is supported in a system you are familiar with. (6 marks) END OF QUESTION PAPER Page 5 of 5