CS151: Digital Design

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CS151 Digital Design

• Chapters 4, 5
• Review

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Question 1

• Design a combinational circuit for a
  Roller-Coaster ride in an amusement park. The
  design should include a truth table, simplified
  Boolean function(s), and logic diagram.
• The Roller-Coaster Safety System has three
  sensors
• Speed this sensor will generate a signal if the
  roller-coaster vehicle exceeds the speed limit
• Safety this sensor will generate a signal if one
  of the seatbelts is unbuckled
• Stability this sensor will generate a signal if
  the roller-coaster moves off the tracks
• The Roller-Coaster Safety System has two output
  features
• Slow this will be activated to slow down the
  vehicle if the Speed sensor was on.
• Shut-down this will be activated to stop the
  roller-coaster if at least two sensors were on.

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4 X 1 Line MUX

• Transmission Gate Multiplexer

Y S0 S1
I0 0 0
I1 1 0
I2 0 1
I3 1 1
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Question 2

• Construct an 8-to-1-line multiplexer with enable
  input using transmission gates.

Y S0 S1 S2
I0 0 0 0
I1 1 0 0
I2 0 1 0
I3 1 1 0
I4 0 0 1
I5 1 0 1
I6 0 1 1
I37 1 1 1
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8 x 1 MUX
Y
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Question 3

• Show that a positive logic NAND gate is a
  negative logic NOR gate.

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Question 4

• Design an Excess-3-to-BCD code converter, that
  gives output code 0000 for all invalid input
  combinations. Your design should include the
  truth table and simplified equations for each
  possible output. Note that possible inputs range
  from the exess-3 codes 0011 (0 decimal) to 1100
  (9 decimal).