JNTU
JNTU B.Tech III DIGITAL SYSTEM DESIGN Previous Question Paper (August/September - 2024 - R16)
Question paper consists of Part A, Part B. Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Answer all questions. (25 Marks)
Outline two major limitations of FSMs with examples.
Answer
The two major limitations of Finite State Machines (FSMs) are state explosion and lack of scalability for complex systems. First, state explosion occurs when the number of states grows exponentially with the number of inputs or internal variables, making the design unmanageable; for example, a system tracking the status of 20 independent sensors would require 220 states. Second, FSMs suffer from lack of modularity and scalability, as adding new features often requires a complete redesign of the state transition logic; for instance, adding a 'pause' function to a simple traffic light controller may necessitate duplicating existing states to account for the new condition, leading to a highly complex and error-prone transition table.
Define the Fundamental Mode Model in the context of digital circuit design.
Answer
The Fundamental Mode Model is a design approach for asynchronous sequential circuits where the circuit operates under the assumption that only one input variable changes at a time, and the next input change does not occur until the circuit has reached a stable state. This model ensures that the internal state transitions are completed before the next input is applied, preventing race conditions and ensuring predictable behavior. In this mode, the circuit is designed such that the time interval between successive input changes is sufficient for all internal feedback loops to settle to a steady state.
State one challenge associated with designing a high-speed binary divider circuit.
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Give an example of a scenario where a PAL would be preferred over a PLA in digital circuit design.
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How are SM charts used in system design?
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How can a State Graph be converted to a State Machine?
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What are the key differences in the approaches of D and PODEM algorithm?
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How can signature analysis techniques be employed to verify the correctness of circuit implementations and detect faults?
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How are machine identification techniques applied to identify and isolate faults in digital systems?
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What are the primary factors to account for when designing experiments to effectively detect and diagnose faults?
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Part B
Answer any one question from each unit. (50 Marks)
Explain the concept of a Finite State Machine (FSM) and discuss its primary capabilities in modeling sequential logic systems.
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Given a set of states and inputs, perform state reduction on the following state table and determine the minimal closed covers:
| Present State(PS) | 00 | 01 | 10 | 11 |
| Next State(NS) | 01 | 10 | 11 | 00 |
| Input(I) | 0 | 1 | 0 | 1 |
| Output(O) | 1 | 0 | 1 | 1 |
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Discuss the importance of reducing the number of states in a design.
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Explain the process of minimizing a Finite State Machine. Apply the minimization algorithm to reduce the following Moore machine:
Present State A A B B C C D
Input 0 1 0 1 0 1 0
Next State B C A D A D B
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Explain the concept of a Read-Only Memory (ROM) and discuss a real-world application where ROMs are commonly used.
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Describe the functions of a controller in a microprogrammed control unit. Also list the trade-offs between hardwired control and microprogrammed control.
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Create a state graph for a Finite State Machine (FSM) that controls an elevator system with functionality for moving between floors and opening/closing doors.
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Implement a 4-bit shift and add multiplier using a HDL. Provide the diagram and describe the operation of the multiplier.
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Explain the concept of State Machine Charts and their significance in the context of system design.
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Design a state machine chart for a simple dice game controller. The system should support rolling the dice, displaying the result, and tracking the score of the player.
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Implement a 3-bit binary multiplier using a State Machine Chart. Provide the detailed design process and the resulting state transitions.
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Describe the process of translating a State Machine Chart into hardware or software implementation. What are the key steps and challenges in this translation process?
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Explain the concept of Redundancy in fault-tolerant design. How can redundancy be effectively utilized to enhance the fault tolerance of digital systems?
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Describe the Kohavi Algorithm and its significance in fault diagnosis. How does the algorithm contribute to the automated detection and localization of faults in digital circuits?
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Describe the Single Stuck-at Fault Model and explain how it is used to represent faults in digital circuits. Provide examples to illustrate the concept.
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Discuss the key steps involved in applying the D algorithm to identify and target fault locations in combinational circuits.
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Discuss the principles and methodology of the Transition Check Approach in digital circuit testing.
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A fault is suspected to occur in the circuit, leading to an incorrect state transition from 01 to 10, causing unexpected output behavior. Designing a fault detection experiment to identify the fault and isolate its location.
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Describe the process of State Identification and Fault Detection Experiment in the domain of digital circuit testing.
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Discuss the different machine identification methods used in fault detection experiments for digital circuits. Compare and contrast the advantages and disadvantages of each method.
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