1. Introduction

The Von Neuman model, on which general-purpose processors are based, distinguishes between :

• the processor that executes the program instructions. This processor owns neither the instructions nor the program data;

• memory, which contains the program and data, but its sole function is storage.

The processor must therefore access instructions and data located in memory.

Since the introduction of MOS technologies, there has been a growing gap between processor performance (instruction throughput) and the performance of DRAM memories used as main memory. This growing gap is known as the "memory wall", as defined by Wulf and Mc Kee in 1994.

Various techniques have been and are being used to limit the growing gap between instruction...