VARDHAMAN COLLEGE OF ENGINEERING
(AUTONOMOUS)
B. Tech VI Semester Regular Examinations, May 2018
(Regulations: VCE-R15)
REAL TIME OPERATING SYSTEMS
(Electronics and Communication Engineering)
Date: 28 May, 2018 FN
Time: 3 hours
Max Marks: 75
Answer ONE question from each Unit
All Questions Carry Equal Marks
Unit I
1.

Explain what a Real time system is with some examples. List and explain the various frequently cited misconceptions with respect to the Real Time systems.
8M

Explain the following terms of Real time Systems with relevant examples:
i. Job
ii. Task
iii. Release time
iv. Absolute deadline
v. Relative deadline
vi. Execution time
vii. Response time
7M
2.

Explain periodic, aperiodic and sporadic tasks with relevant examples. Enumerate any two applications of real-time systems.
8M

Job_1 Job_2 denotes a pipe: The result produced by job_1 is incrementally consumed by job_ 2. (As an example, suppose that job_2 reads and displays one character at a time as each handwritten character is recognized and placed in a buffer by job_1.) Draw a precedence constraint graph to represent this producer-consumer relation between the jobs.
7M
Unit II
3.

What is a Real Time kernel? Explain the role of kernel in operating systems with a neat figure of layers of operating system functionality and its associated taxonomy.
7M

Examine the Priority Inversion problem in RTOS with an example. Explain the methods to overcome the priority inversion problem.
8M
4.

Define a Process. Illustrate the different states and their transitions among them with a neat figure of process state diagram as a partially defined finite state machine.
7M

What is semaphore? Explain the different types of semaphores. Examine the various problems associated with semaphores and how it can be overcome.
8M
Unit III
5.

Illustrate how process stack management is implemented using the run-time stacks and the task-control block models with relevant example.
7M

Write a short note on time garbage collection system.
8M
6.

Explain the features, working and advantages of the Block or Page Management technique for memory management with example. Illustrate how this page management technique is used to address the fragmentation problem.
7M

Which of the following systems of periodic tasks are schedulable by the rate-monotonic algorithm and earliest-deadline-first algorithm? Justify your answer:
i.
ii.
iii.
8M
Cont…2

Unit IV
7.

Explain the desirable characteristics of real time systems.
8M

With a neat block diagram, explain the central processing unit of a real time system.
7M
8.

Illustrate the features of the following standardized and customized systems interfaces used in embedded real-time systems with relevant figures:
i. MIL-STD-1553B
ii. Small Computer Systems Interface
iii. IEEE 1394 Firewire
8M

Identify the various single and multi peripherals that are required for interfacing devices to the CPU via interrupts.
7M
Unit V
9.

Illustrate the features of Packet switched Networks in the Real time systems. communication with a neat figure of multi-hop switched network and a 4 x 4 switch. Also explain the taxonomy of service disciplines.
8M

List and explain the common POSIX I/O operations typically found in real-time systems. Also explain the associated Data Structures used for Asynchronous Input and Output with examples.
7M
10.

Illustrate the features of Weighted Fair queuing Discipline for switched networks.
8M

Illustrate how the real time communication is implemented in Multi computer systems.
7M