Research and development in multistate fluid logic elements is reviewed in a historical and critical report. The report concludes that in the development of fluid amplifiers, there are elements with very high gain and poor switching speed, and other elements with very high switching speed and poor gain

Reader, T.

English

NASA Technical Reports Server

November 1967
	 Brief 67-10438 
NASA TECH . BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Review of Research and Development in Fluid Logic Elements 
A report has been prepared that reviews, histori-
cally and critically, the present state of research and 
development in multistate fluid elements. The report 
concludes that the development of fluid amplifiers is 
at the crossroads in that there are elements with very 
high gain and poor switching speed, and other ele-
ments with very high switching speed and poor gain. 
The former elements have been conventionally classed 
as active, while the latter have been classed as pas-
sive. In the light of recent advances, however, this 
distinction has become less meaningful. It is now anti-
cipated that there will be a synthesis of active and 
passive principles so that speed may be combined with 
adequate gain. 
The report considers four classes of multistate 
elements: 
1. Multilevel with memory 
2. Multilevel without memory 
3. Multioutput with memory 
4. Multioutput without memory 
Tests have shown that the only satisfactory ele-
ments which could be built were in classes 3 and 4. 
The class 3 element found at least one useful appli-
cation, the asynchronous shift register, but was rela-
tively slow. The class 4 element has, however, been 
shown to be a powerful logic element with a capacity 
for high speed and an insensitivity to small geometric 
variations not found in any other class of element. 
Tests carried out on class 4 elements suggest that 
operation at very low Reynolds numbers should be 
possible although insufficient quantitative data have 
been obtained to show what the lower limit might be. 
It appears from these conclusions that future in-
vestigations should involve class 4 elements used in 
conjunction with amplifiers of moderate gain. Tests
should be conducted on complex circuits to determine 
system reliability and speed. A parallel effort should 
be made to determine the scope of recent concepts in 
bionics in which it appears that limitations of speed 
may be overcome by asynchronous polymorphic logic 
in much the same manner that the brain apparently 
overcomes these limitations. Majority logic and vari-
able threshold logic elements may be synthesized from 
the basic fluid elements that have been developed. It 
is now conceivable that miniature fluid elements may 
be integrated to form thousands of interconnecting 
"neurons" to perform that quasi-digital type of logic 
now associated with the brain. If this should prove 
feasible, the state of the art would be one step closer 
to the adaptive machine having high-order artificial 
intelligence. 
Note: 
Additional details are contained in: Research and 
Development in Fluid Logic Elements, by T. Reader, 
Sperry Rand Corporation, NASA CR-61029, Decem-
ber 1964. Copies are available from: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10438 
Patent status: 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to NASA, 
Code GP, Washington, D. C. 20546.
Source: T. Reader

of Sperry Rand Corporation

under contract to

Marshall Space Flight Center

(M FS-420) 
Category 01 
L
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000438 2020-03-11T21:13:59+00:00Z


Review of research and development in fluid logic elements

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server