Report Number: CSL-TR-89-400
Institution: Stanford University, Computer Systems Laboratory
Title: Sparse distributed memory prototype: principles and operation
Author: Flynn, Michael J.
Author: Kanerva, Pentti
Author: Bhadkamkar, Neil
Date: December 1989
Abstract: Sparse distributed memory is a generalized random-access memory (RAM) for long (e.g., 1,000 bit) binary words. Such words can be written into and read from the memory, and they can also be used to address the memory. The main attribute of the memory is sensitivity to similarity, meaning that a word can be read back not only by giving the original write address but also by giving one close to it as measured by the Hamming distance between addresses. Large memories of this kind are expected to have wide use in speech recognition and scene analysis, in signal detection and verification, and in adaptive control of automated equipment---in general, in dealing with real-world information in real time. The memory can be realized as a simple, massively parallel computer. Digital technology has reached a point where building large memories is becoming practical. This research project is aimed at resolving major design issues that have to be faced in building the memories.This report describes the design of a prototype memory with 256-bit addresses and from 8K to 128K locations for 256-bit words. A key aspect of the design is extensive use of dynamic RAM and other standard components.