The IEEE/ANSI symbol for a decoder has the internal designation bcd/dec. This me

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Question
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.

Correct Answer

BCD-to-decimal decoder with four inputs and ten outputs.

MSI Logic Circuits problems

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1. 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

2. 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

5. 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.

6. 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

7. 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

8. Refer to the display multiplexer given below. The MSD display is blank, while the LSD seems to be OK. The input and output lines to the 74157 and 7449 are checked with a scope and can be seen changing levels. The A input on the 74139 also changes; however, the 0 output on the 74139 is always LOW and the 1 output is always HIGH. The B and EN inputs on the 74139 are always LOW. What could cause the problem and what should be done to correct it?
Options
A. The 74139 is defective; replace it.
B. The EN pin on the 74139 could have a bad connection; check the connection.
C. The 74139 is defective and must be replaced; or the EN pin on the 74139 could have a bad connection, which should be checked.
D. The MSD display is bad; replace it.

9. For the input values (A0?A3, B0?B3, Data Select = 1) given for the circuit given below, what will be indicated on the displays?
Options
A. A = 0, B = 5
B. A = 5, B = 0
C. A = 6, B = 0
D. A = 0, B = 6

10. The circuit in Figure 9-8 is defective; data is not appearing on the output lines. A check with the scope shows data pulses on the serial data line and multiplex control lines, S0?S2; no parity error is indicated. A further check with a logic probe indicates that V_cc and ground appear to be present. What might be wrong with the circuit?
Options
A. The demultiplexer may be bad.
B. The parity checker is defective.
C. The parity generator may be bad.
D. The parity checker is defective, or the parity generator may be bad.

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