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Tuesday, 28 April 2015

Computers as Components- Model question paper for B.E/B.Tech Engineering



1(a) Draw a state diagram for a behaviour that sends the command bits on the track. The machine should generate the address, generate the correct message type, include the parameters and generate the ECC. (6 Marks)
(b) Briefly describe the distinction between specification and architecture. (4 Marks)
(c) What is the difference between the Harvard and von-Neumann architectures? (4 Marks)
(d) Write a program that uses a circular buffer to perform FIR filtering. (6 Marks)
2(a) Draw a UML sequence diagram that shows how an ARM processor goes into supervisor mode. The diagram should include the supervisor mode program and the user mode program. (8 Marks)
(b) Write ARM code that tests a register at location ds 1 and continues execution only when the register is nonzero. (4 Marks)
(c) What is the difference between latency and throughput? (4 Marks)
(d) If we want an average memory access time of 6.5 ns, our cache access time is 5ns, and our main memory access time is 80 ns, what cache hit rate must we achieve? (4 Marks)
3(a) Draw a UML sequence diagram showing a write operation with wait states across a bus bridge. (8 Marks)
(b) What happens when an interrupt handler executes for too long and the next interrupt occurs before the last call to the handler has finished? (4 Marks)
(c) If you have a choice among several DRAMs of the same capacity but with different data widths, when would you want to use a narrowpower memory? When would you want to use a taller memory? (4 Marks)
(d) What is a logic analyzer? (4 Marks)
4(a) Assume you want to use random tests on an FIR filter program. How would you know when the program under test is executing correctly? (4 Marks)
(b) Write a C code for a program that takes two values from an input circular buffer and puts the sum of those two values into a separate output circular buffer. (8 Marks)
(c) Explain why the person generating clear-box program tests should not be the person who wrote the code being tested. (4 Marks)
(d) What is Frequency-shift keying? Explain. (4 Marks)
5(a) Distinguish between Round-robin scheduling and Cyclostatic scheduling. (4 Marks)
(b) How would you use the ADPCM method to encode an unvarying (DC) signal with the coding alphabet {-3, -2, -1, 1, 2, 3}? (4 Marks)
(c) What factors provide a lower bound on the period at which the system timer interrupts for preemptive context switching? (4 Marks)
(d) Draw a UML class diagram for a process in an operating system. The process class should include the necessary attributes and behaviours required of a typical process. (8 Marks)
6(a) You are designing an embedded system using an Intel Xeon as a host. Does it make sense to add an accelerator to implement the function z=ax+by+c? Explain. (4 Marks)
(b) Determine how much logic in an FPGA must be devoted to a PCI bus interface and how much would be left for an accelerator core. (8 Marks)
(c) Draw and explain the sequence diagram and object diagram for the video accelerator. (8 Marks)
7(a) Give an example of a simple protocol that would allow sensor nodes in a sensor network to determine the other nodes with which they can communicate. (4 Marks)
(b) Explain the seven layers of OSI model. (8 Marks)
(c) Explain how I2C Bus can be used to link microcontrollers into systems. (4 Marks)
(d) What is the longest time that a processing element may have to wait between two successive data transmissions on a round-robin arbitrated bus? Assume that each data transmission requires one time unit. (4 Marks)
8(a) Differentiate between waterfall model, spiral model and successive refinement model of system design techniques. (6 Marks)
(b) what is CRC card methodology? Explain the steps to follow while using this methodology to analyze a system. (6 Marks)
(c)What skills might be useful in a cross-functional team that is responsible for designing a set-top box? (4 Marks)
(d) Estimate the cost of finding and fixing a single software bug. (4 Marks)

Monday, 27 April 2015

Introduction to embedded systems- Model question paper for B.E/B.Tech Engineering



1(a) Explain different classifications of embedded systems. Give an example for each. (4 Marks)
(b) What is Programmable Peripheral Interface (PPI) device? Explain the interfacing of 8255 PPI with an 8-bit microprocessor/controller. (8 Marks)
(c) What is embedded Firmware? What are the different approaches available for Embedded Firmware Development? (4 Marks)
(d) Give an overview of the different market players of the automotive embedded application domain. (4 Marks)
2(a) What is non-operational quality attribute? Explain the important non-operational quality attributes to be considered in any embedded system design. (4 Marks)
(b) Explain the code memory organization for 8051 for internal and external program memory access. (8 Marks)
(c) Explain how port 3 acts as a normal I/O port and an alternate I/O function port? (4 Marks)
(d) What are the different techniques that can be adopted for reducing the power consumption of an 8051 based system. (4 Marks)
3(a) Write a 8051 assembly language program to find the largest number from an array of 10 numbers. The array is located in the data memory and the start address of the array is 20H. (8 Marks)
(b) Explain the difference between LCALL and ACALL for subroutine invocation. Which one faster in execution and why? (4 Marks)
(c) What is the difference between Finite State Machine Model (FSM) and Hierarchical/Concurrent Finite State Machine Model (HCFSM)? (4 Marks)
(d) What is computational model? Explain its role in hardware software co-design. (4 Marks)
4(a) What is a combinational circuit? Draw a combinational circuit for embedded application development. (6 Marks)
(b) What is the use of BoM in embedded hardware design and development? (4 Marks)
(c) Explain the different PCB fabrication techniques. State the merits and drawbacks of each. (6 Marks)
(d) Explain the difference between synchronous and asynchronous sequential circuits. Give an example each. (4 Marks)
5(a) What is the difference between ‘Super loop’ based and ‘OS’ based embedded firmware design? Which one is the better approach? (4 Marks)
(b) Explain the different sections of a memory segment allocated to an application by the memory manager. (4 Marks)
(c) What is structure padding? What are the merits and demerits of structure padding? (4 Marks)
(d) Write a small embedded C program to set bit 0 and clear bit 7 of the status register of a device, which is memory mapped to the CPU. The status register of the device is memory mapped at location 0x8000. The data bus of the controller and the status register of the device is 8bit wide. The application should illustrate the usage of bit manipulation operations. (8 Marks)
6(a) Explain the different task communication synchronization issues encountered in Interprocess Communication. (4 Marks)
(b) What is virtual memory? What are the advantages and disadvantages of virtual memory? (4 Marks)
(c) Explain starvation in the process scheduling context. Explain how starvation can be effectively tackled. (4 Marks)
(d) Write a Win32 console application illustrating the usage of anonymous pipes for data sharing between a parent and child processes using handle inheritance mechanism. Compile and execute the application using Visual Studio under Windows XP/NT OS. (6 Marks)
7(a) What is Semaphore? Explain the different types of semaphores supported by VxWorks. (4 Marks)
(b) Explain different mutual exclusion mechanisms supported by MicroC/OS-II kernel. State the relative merits and limitations of each. (6 Marks)
(c) Explain major drawbacks of out-of-circuit programming. (4 Marks)
(d) What are the different techniques available for embedded firmware debugging? Explain them in detail. (6 Marks)
8(a) What is rapid prototyping? What are the different techniques available for rapid prototyping? Explain the merits and limitations of each. (6 Marks)
(b) Explain the various activities performed during the ‘requirement analysis’ phase of an embedded product development. (6 Marks)
(c) Explain the similarities and differences between ‘Iterative’ and ‘Incremental’ life cycle model. (4 Marks)
(d) Write a short note on ‘Openmoko’. (4 Marks)

Saturday, 18 April 2015

Power electronics-Model question paper for Diploma/B.E/B.Tech



1(a) Explain how practical switches deviate from ideal switches in their characteristics. (4 Marks)
(b) With a neat circuit diagram and waveforms, explain the principle of working of a step-down chopper connected to a resistive load. (8 Marks)
(c) Explain peripheral effects caused by power electronic converters. (4 Marks)
(d) The reverse recovery time of a diode is 5μs and the rate of fall of diode current is 80 A/μs. If the softness factor is 0.5, determine storage charge and peak reverse current. (4 Marks)
2(a) Explain the need for isolating the control terminals of a semiconductor switch from the triggering source and how to do this. (8 Marks)
(b) Give reasons why power BJTs have been replaced by power MOSFETs and IGBTs in modern power electronic applications. (8 Marks)
(c) Explain the method of calculation of average power loss in a semiconductor switch. (4 Marks)
3(a) With a neat sketch, explain the two transistor model of an SCR. Obtain the condition for turn ON and turn OFF the device. (8 Marks)
(b) Describe thermal model of a thyristor. (4 Marks)
(c) Distinguish between latching current and holding current of an SCR. (4 Marks)
(d) A 450 A thyristor is operated in parallel with a 550 A thyristor. The ON-stage voltage drops of the thristors at these rated currents are 1.8 V and 1.2 V respectively. Estimate the resistance to be connected in series with each thyristor in order that the y share a total load current of 1000 A in proportion to their current ratings. (4 Marks)
4(a) With necessary circuit diagrams and waveforms explain complementary communication. (8 Marks)
(b) What is commutation? What are the methods of commutation? Explain auxiliary commutation. (8 Marks)
(c) State the conditions to be satisfied for proper turn OFF of an SCR. (4 Marks)
5(a) With necessary circuit diagram and waveforms describe the operation of a single-phase half-wave ac controller. Derive an expression for the RMS value of output voltage and current. (8 Marks)
(b) Explain with relevant circuit diagrams and waveforms the working of a single-phase phase control type AC voltage controller connected to R-L load and obtain a relationship between the rms output voltage and the rms input voltage. (8 Marks)
(c) The input voltage to a single-phase half wave ac voltage controller is 230 V, 50 Hz. If it delivers an output power of 3 kW to a resistor load of 15 Ohm, find the delay angle of the thyristor and input power factor. (4 Marks)
6(a) Explain the working of single-phase half-wave controlled rectifier connected to resistive load and derive a relationship between the average output voltage and input voltage. (8 Marks)
(b) Explain the working of a three-phase full converter connected to a highly inductive load with ripple-free load current. (8 Marks)
(c) A three-phase full converter is operated from a three-phase 50 Hz ac supply and the load current is constant under steady operating conditions. Determine the firing angle for the SCRs to obtain an output average dc voltage of 50% of the maximum. If the output voltage is 270 V, calculate the ac supply line-to-line rms voltage. (4 Marks)
7(a) What is a chopper. Explain different control strategies for choppers. (4 Marks)
(b) With power circuit diagram and waveforms of voltages and currents explain the working of impulse commutated chopper. State clearly all the simplifying assumptions made in the analysis. (8 Marks)
(c) A step-up dc chopper has an input voltage of 200 V and an output voltage of 250 V. The blocking period in each cycle is 0.6 ms. Find the period of conduction in each cycle. (4 Marks)
(d) A thyristor chopper is supplying an inductive load with R= 5 Ohm and L= 500 mH. The dc supply to the chopper is 250 V. If the chopper is operating at a frequency of 500 Hz and ON/OFF time ratio of the chopper is 1:2, calculate average load current and maximum/minimum values of load current in one cycle of chopper operation under steady state conditions. (4 Marks)
8(a) Explain the modified sinusoidal-pulse width modulation technique of varying the magnitude of output voltage in a single-phase inverter. (6 Marks)
(b) Explain the phase displacement technique of varying the magnitude of output voltage in a single-phase inverter. (6 Marks)
(c) Define the performance parameters of inverters. (4 Marks)
(d) A single-phase full bridge inverter employs single-pulse width modulation technique to control the output voltage. What should be the pulse width for the rms value of the fundamental component of the output voltage to be 60% of the dc input voltage? (4 Marks)

Wireless and mobile communication-Model question paper for Diploma/B.E/B.Tech



1(a) Why is PSTN required for wireless communication? (4 Marks)
(b) What is TDMA? Explain its advantage and disadvantage over FDMA. (6 Marks)
(c) Explain packed radio using ALOHA techniques. (4 Marks)
(d) Why is CDMA most secure than other multiple access techniques? Explain basic operation of CDMA. (6 Marks)
2(a) Explain the differences between wireless and fixed telephone networks. (4 Marks)
(b) Explain characteristics and functions of SS-7 network and protocol. (8 Marks)
(c) Write a note on cellular digital packet data. (4 Marks)
(d) Mention some advantages of packet switching. (4 Marks)
3(a) Explain frequency reuse concept. How it is used to increase cellular system capacity? Explain using a suitable example. (8 Marks)
(b) Write a note on umbrella cell approach. (4 Marks)
(c) Derive formula for signal-to-interference ratio. (4 Marks)
(d) If a service provider had a 10.5 MHz band in each direction (up-link and down-link) and it would install 20 antenna sites to provide its services, what would be the maximum number of simultaneous users that the system called support in all cells? Neglect the channels that are used for control signaling. (4 Marks)
4(a) Explain using a block diagram, first generation basic cellular radio network. (8 Marks)
(b) Describe three subsystems in the GSM architecture. (6 Marks)
(c) Write a note on identification codes in AMPS. (6 Marks)
5(a) What is GPRS? Explain its architecture and services it provides. (8 Marks)
(b) What are the reasons to perform handoff? (6 Marks)
(c) What is location management system? What is the difference between registration and call establishment? (6 Marks)
6(a) Mention some advantages and disadvantages of WLAN compared to Wired LAN. (6 Marks)
(b) All current WLAN products fall into one of the three categories. Explain. (6 Marks)
(c) What is ad-hoc networking? (4 Marks)
(d) Distinguish between LLC and MAC. (4 Marks)
7(a) Explain the difference between piconets and scotternets. With reference to this, explain Bluetooth architecture. (8 Marks)
(b) Write a note on RFCOMM protocol. (4 Marks)
(c) Write a note on Bluetooth security. (4 Marks)
(d) What is the difference between the MAC protocol of the Bluetooth and the IEEE 802.11? (4 Marks)
8(a) Explain microcell zone concepts. (6 Marks)
(b) Explain spectrum allocation. Explain the difference between analog and digital cellular systems. (8 Marks)
(c) Distinguish between Hata model and Walfisch-Bertoni model. (6 Marks)