ECE 171: Introduction to Digital Circuits

Fall 1999

Rev: 11.15.99

Exam 2 Topics

This page lists the topics that may be included in Exam 2.

Logistics

• Please turn off your cell phones and pagers during the exam.
• You are allowed a single double-sided page of notes or two single-sided page of notes.
• You are allowed to use a calculator, but you will not need it.
• Count the number of pages to make sure you have all of them.
• Write your student ID at the top of each sheet. You will lose points this time if you do not do this.
• Since we covered Karnaugh maps in much greater detail than the book, you are strongly encouraged to study the extensive lecture notes on this topic and the homework solutions.

Topics

• Logic Diagrams
  You should know how to draw a logic diagram from a boolean expression, truth table, or karnaugh map using just NAND gates or just NOR gates.
• Boolean Algebra
  You should know how to simplify a Boolean expression using the 32 rules of Boolean Algebra that we discussed in class.
• Karnaugh Maps
  You should know Karnaugh maps very well. There will not be a 6-variable map on the exam, but you should know how to use up to 5-variable maps for the exam. You should also be able to identify and count the prime implicants, distinguished one cells, essential prime implicants and minimal sums. You should also know how to incorporate don't cares and know how to use Karnaugh maps to generate minimal products.
• Encoders/Decoders
  You should understand how encoders and decoders work.
• Multiplexers/Demultiplexers
  You should know how multiplexers and demultiplexers work. You should also know how to use multiplexers to make a multiplexer tree and how to use multiplexers to implement combinational logic. You should understand how to connect a multiplexer to a demultiplexer in a serial communications application.
• Parity
  You should know why parity is used, how exclusive-or trees are used to implement parity generators/checkers, and how to determine if a set of wires has odd parity or even parity.
• PLD's
  You should be familiar with the internal structure of PROM's and PAL's and know how to specify which wires should be connected internally to implement a particular function.
• Static Hazards
  You should know how to eliminate static-1 hazards in two-level AND-OR circuits and how to eliminate static-0 hazards in two-level OR-AND circuits.
• Seven Segment Displays
  You should know what common-anode and common-cathode displays are. You should know how to connect the output of a gate to a seven segment display. You should also know why resistors have to be used in connecting gates to these displays. You should understand how the 74LS47 described in the book and lecture can be used to drive these displays or a bank of these displays.