# 1. Objective

This experiment will be a little different than the previous labs. You will be placed in a (pseudo) real world design situation, and asked to complete a design using a limited number of parts and part types. You should use your skills for representing logic functions in different ways, your skills with LogicWorks, and your problem solving skills to complete this design.

# 2. Materials that you need

For this experiment you will need the following equipment:

• proto board with logic probes and switches.
• 1 74`00 (quadruple 2-input NANDs)
• 1 74`02 (quadruple 2-input NORs)
• 1 74`10 (triple 3-input NANDs)

(See the data sheets for the lab for descriptions of the circuits.)

# 3. Prelab

1. Read over the lab sections of this experiment. Be sure you understand what is to be done.
2. Show how your ``partner'' (who is described in subsequent sections) used an `02 device as a voltage inverter in Figure 2.
3. Try to solve the puzzle posed below and complete the design as much as you can. In your prelab write-up, document (with Xilinx Circuit Diagrams) the implementation of the three functions in ``Magic'' described below. If you cannot solve the puzzle before the lab, do the ``best'' design you can. TA may be able to give you hints in the lab.
4. Prepare any tables you think you will need to verify the operation of the ``Magic'' box.

# 5. The Puzzle --- Minimizing the Design

You take a look at your partner's design notebook at home, and see that she has done a pretty good job, so far. She has called her module ``Magic'', and drawn a block diagram as shown in Figure 1 with four inputs; Ab, Ber, Ca, and Daber, and three outputs; Hither, Dither, and Yon.

Figure 1. Block Diagram for Magic

Unfortunately, the page with the word description of the ``Magic'' box is missing from the design book, but your partner has begun the design work on the three functions. She has completed the Circuit Diagram for the function Hither as seen in Figure 2 and derived a Truth Table for Dither as seen in Table 1.

Figure 2. Circuit Diagram for Hither

Table 1. Truth Table for Dither

You also find a Maxterm expansion for the function, Yon as follows:

Looking over the notebook, you see that so far, there are three chips that are needed; a 74`00, 74`02, and 74`10. The last entry your partner made before going to lunch is scrawled in the margin. It says:

``I've been staring at these K-Maps for hours, and I finally see how to implement Dither.H and Yon.L without adding any more chips to the board!''

# 6. What You Turn In

Your job is to figure out what she meant by that and finish this design. Then you should simulate, build and test it.

Your lab write-up should include the final Circuit Diagrams together with Truth Tables for each function showing expected, simulated and measure values.

(Hint: Draw K-maps and see if there's a relationship between them.)