Asynchronous Circuit Design

1

Introduction

Wine is bottled poetry.

—Robert Louis Stevenson

Wine gives courage and makes men more apt for passion.

—Ovid

I made wine out of raisins so I wouldn't have to wait for it to age.

—Steven Wright

In this chapter we use a simple example to give an informal introduction to many of the concepts and design methods that are covered in this book. Each of the topics in this chapter is addressed more formally in much more detail in subsequent chapters.

1.1 PROBLEM SPECIFICATION

In a small town in southern Utah, there's a little winery with a wine shop nearby. Being a small town in a county that thinks Prohibition still exists, there is only one wine patron. The wine shop has a single small shelf capable of holding only a single bottle of wine. Each hour, on the hour, the shopkeeper receives a freshly made bottle of wine from the winery which he places on the shelf. At half past each hour, the patron arrives to purchase the wine, making space for the next bottle of wine. Now, the patron has learned that it is very important to be right on time. When he has arrived early, he has found an empty shelf, making him quite irate. When he has arrived late, he has found that the shopkeeper drank the last bottle of wine to make room for the new bottle. The most frustrating experience was when he arrived at just the same time that the shopkeeper was placing the bottle on the shelf. In his excitement, he and the shopkeeper collided, sending the wine bottle to the floor, shattering it, so ...