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  • Question
  • Which is the decimal number for the BCD number, 10110110?


  • Options
  • A. 182
  • B. 36
  • C. 116
  • D. 10110110 is not a valid BCD number.

  • Correct Answer
  • 10110110 is not a valid BCD number. 


  • MSI Logic Circuits problems


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    • 1. Output 5 of a 74138 octal decoder is selected when it is enabled by a data input of:

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 2. Refer to the keyboard encoder in figure (a). Sometimes when the 5 key is pressed, the system attached to the keypad does not respond. The 5 input on the 74147 is monitored with a digital storage scope while repeatedly pressing the 5 key, and the waveform in figure (b) is obtained; the P above the trace indicates the points at which the technician pressed the key. What is most likely wrong with the circuit?


    • Options
    • A. The switches on the 5 key are intermittent; the contacts need to be cleaned or the switch replaced.
    • B. The pull-up resistor connected to the 5 key is bad and should be replaced.
    • C. The common ground connection at the bottom of the 0 key has a bad solder connection; repair the connection.
    • D. The 74147 is intermittent, possibly due to high temperature, and should be replaced.
    • Discuss
    • 3. It is suspected that the comparator in the figure given below has a problem. The inputs are activated in the table shown below and the corresponding outputs noted. What is most likely wrong with the circuit?
      For P0 ? P3 = 1 and Q0 ? Q3 = 0, P > Q = 1, P = Q = 1, P < Q = 0
      For P0 ? P3 = 0 and Q0 ? Q3 = 1, P > Q = 0, P = Q = 1, P < Q = 1
      For P0 ? P3 = 1 and Q0 ? Q3 = 1, P > Q = 0, P = Q = 1, P < Q = 0


    • Options
    • A. The P0?P3 inputs are defective.
    • B. One or more of the Q inputs is bad.
    • C. The P = Q output is shorted to Vcc.
    • D. Nothing is wrong; the circuit is functioning properly.
    • Discuss
    • 4. Referring to the figure given below, what output code will appear on the output (A3,A2,A1,A0) when the 5 key is pressed?


    • Options
    • A. 1010
    • B. 0101
    • C. 1101
    • D. 1011
    • Discuss
    • 5. What is the purpose of a decoder's inputs?

    • Options
    • A. To allow the decoder to respond to the inputs to activate the correct output gate.
    • B. To disable the decoder outputs so that all outputs will be inactive.
    • C. To disable the inputs and activate all outputs.
    • D. To allow the decoder to respond to the inputs to activate the correct output gate, and to disable the inputs and activate all outputs.
    • Discuss
    • 6. What type of device is shown in the given figure, and what inputs (A3,A2,A1,A0) are required to produce the output levels as shown?


    • Options
    • A. A binary-to-decimal encoder; 0,1,1,1
    • B. A decimal-to-binary decoder; 1,1,1,0
    • C. A BCD-to-decimal decoder; 0,1,1,1
    • D. A decimal-to-BCD encoder; 1,1,1,0
    • Discuss
    • 7. What is an important attribute of the conditional signal assignment statement?

    • Options
    • A. Its tristate outputs
    • B. Its sequential evaluation
    • C. Its use of library components
    • D. Its fast activation times
    • Discuss
    • 8. The IEEE/ANSI symbol for a decoder has the internal designation bcd/dec. This means the decoder is a:

    • Options
    • A. decimal-to-BCD decoder with ten inputs and four outputs.
    • B. BCD-to-decimal decoder with ten inputs and four outputs.
    • C. decimal-to-BCD decoder with four inputs and ten outputs.
    • D. BCD-to-decimal decoder with four inputs and ten outputs.
    • Discuss
    • 9. What VHDL techniques are used to describe a priority encoder?

    • Options
    • A. Integer outputs and priority coding
    • B. Signal outputs and priority coding
    • C. Tristate outputs and priority coding
    • D. Variables and priority coding
    • Discuss
    • 10. In an AHDL BCD to binary code converter, how is multiplication by 10 accomplished?

    • Options
    • A. By using the shifting of bits
    • B. By using the library multiplication function
    • C. By using integer types
    • D. By using the multiplication operator
    • Discuss


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