Assignment 4, due Oct. 19, 2005

Read:

Chapter 1 (pp. 1-31) of C. Schaffer, Principles of Computer Science, Prentice-Hall, Englewood Cliffs, NJ, 1988: "Logic with Electricity". This book is on reserve for FRS 119 in both Firestone and the Engineering Library. We've already covered at least half of this material in one way or another.

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Problems:

1. and 2. Schaffer's valve is what I called a "normally closed" valve in class. That is, its output is 1 when and only when its input is 1 (VOLTAGE ON) and its control is 0 (VOLTAGE OFF). We'll use his symbol:

Just to be clear, I'll call this a "normally closed valve", or NC-valve.
The first two problems are from Schaffer:



3. I'll call a "normally open valve" a NO-valve. Such a valve has an output of 1 when and only when its input is 1 and its control is 1.

(a) Construct an AND gate using only NO-valves.

(b) Construct an OR gate using only NO-valves.

4. Mention at least three important differences between the schemes in Yurke et al. 99 (home page --> reading) and Adleman 94 (home page --> reading). The more differences you can mention, the better.

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