Homework Problems for CS 3750

Directions for homework submissions

Format

• Everything except source code (including "psuedo-code"): Turn in hard copy. Double space. Make margins of between 1" and 1-1/4" on sides, top and bottom. Use a font size from 10 to 14. (I prefer a fixed-width font.) Turn in the printout at the beginning of class on the due date.
  
  
• Source code: Turn in a neat, compilable copy by e-mail. No attachments, please. No more than 70 characters per line. The e-mail must be sent before midnight on the due date.
  
  

• Based on your reading of the first chapter, write a concise essay describing the important functions and responsibilities of a modern time-sharing operating system. Write 500 words or more.

1. The HAL 3000 computing system has a primary memory X and a secondary memory Y. HAL also has a cache C that it uses to reduce the average time required to move a word of data from Y to X. Write a pseudo-code algorithm for a function read(A, B) that places a copy of the word at address B in Y into the word at address A in X. (Your algorithm does not have to be very detailed, but it is important that you show you understand how to properly select and sequence the cache-maintenance actions and the memory-transfer actions.)
   
   
2. The summary section of the second chapter states: "Multiprogramming and time-sharing systems improve performance by overlapping CPU and I/O operations on a single machine." Suppose that initially in such a system there is no I/O occurring and a user-program is executing in the CPU. What chain of events would typically change that situation into one where a user-program is executing and I/O is occurring simultaneously? When you answer this, don't skimp on details. Show me that you learned the information in the text that applies here.

• For each of the indicated system calls in the list below, write a few sentences summarizing what tasks the operating system might have to perform to implement the system calls.
  
  (For example, creating a file would require that an entry be placed in some directories or tables on the disk, perhaps some allocation of disk blocks.)
  
  Try to be thorough and include enough plausible detail. I think basically you need to consider what resources have to be allocated/deallocated and what kinds of records are required to keep track of the changes.
  
  Remember your intended audience -- the student who has the prerequisites for this course. Make your answer undestandable and enlightening to your audience.
  
  It is to be understood that there is no one correct way to implement a system call.
  
  
  • load process
  • open file
  • request device
  • set process attributes
  • delete communications session

• Write a small essay in your own words on the topic of programs, processes, and threads. Concentrate on defining each of the three concepts, and on clarifying the similarities and differences among them. Use information distilled from your readings of chapters 4-5, and add whatever else you think will be helpful. (Keep in mind the "intended readership" described in the directions above.)

• Do problem 6.3 on page 185 (this involves making Gantt charts and calculating measures of the performance of several scheduling algorithms).

• Do the problem in the file hymanProb.html in this directory. Please take note of the example "scenario" described in the problem statement. Make sure that the solution you construct is the same kind of specific and detailed scenario.
  
  
• Do Problems 7.1, and 7.6 (Remember to use exposition suitable to your "intended audience" -- a student who has the prerequisites for this course.)
  
  
• Give a pseudo-code solution to the readers-writers problem. Your solution must not let readers starve, nor let writers starve. To achieve synchronization, use only one or more semaphore(s) of the type described in section 7.4.2. Assume that the list in every semaphore is a FIFO queue.
  
  

• Do problem #8.13 on page 269. Show all your work (in detail)..
  
  

• Do the following problem. Show all work in detail.
  
  A virtual address of 76543656 (hex) appears in a program that is being run on a computer that does demand paging. The computer has 24-bit physical addresses, 32-bit virtual addresses, and a 1K-word page-size. How many physical frames are there? How many virtual pages are there? What are the page number and the offset corresponding to the virtual address? (Give the last two both in hex notation and decimal notation.)
  
  
• Do problem #10.10 on page 367. Show all your work in detail and explain all your reasoning in detail.