ASSIGNMENT - I

This assignment is for 20 marks. Each question is worth 5 marks. Please write your answers on A4 pages and submit them to me.

1. Read the section on personal computer systems from the text-book and explain how TSR programs allow operating systems to achieve the effect of multiprogramming without actually being multiprogramming systems. Also, search the Internet for information on TSR programs and the problems with them in MSDOS.
2. Explain how atomic actions are implemented at the hardware level. Use your knowledge of Computer Organisation!
3. What are threads? Explain how threads are used to improve efficiency and utilisation of resources.
4. The following data shows the arrival times and process lengths for execution.

   PID	Arr Time	Length
   1000	0	4
   1001	0	5
   1002	0	8
   1003	1	1
   1004	2	1
   1005	2	6
   1006	3	6
   1007	3	6
   1008	4	2
   1009	4	2
   1010	5	6
   1011	5	7
   1012	6	8
   1013	7	2
   1014	7	9
   1015	8	2
   1016	8	10
   1017	9	2
   1018	9	3
   1019	9	4

   Write a program to compute the waiting time and total time taken to execute all the processes using

   • First-Come-First-Served
   • Shortest-Job-First
   • Round-Robin with a time quantum of 1 unit
   • Highest-Response-Ratio-Next
   scheduling algorithms. Assume that the scheduler looks at the process tables once every 1 time unit and makes decisions on which process to schedule.

The programs need to be demonstrated to me during the lab on 19 September.