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Since then I have added material occasionally.
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Lehmer Factoring Machines
Photo-electric,Chain, Gear
Manufacturer
| D.H. Lehmer
|
Identification,ID
| X85.82
|
Date of first manufacture
| 1932
|
Number produced
| 1
|
Estimated price or cost
| -
|
location in museum
| -
|
donor
|
- Photoelectric machine - D.H. Lehmer
- Chain machine - " ... chain machine - replicated at the (Boston) Computer Museum by
Roberto Canepa, Andrew Kristoffy and
Richard Rubinstein."
|
The above two machines were combined on this page
as the principles of operation are identical,
even though the mechanical details differ.
Contents of this page:
Photo
Photoelectric Factoring Machine
|
Bicycle Chain Factoring Machine - reproduction
|
Placard
Architecture
The Factoring Machines did NOT use the technique of
Eratosthenes
The Lehmers were after much bigger fish - please see
|
Special features
Historical Notes
from http://www.netlib.org/na-digest-html/91/v91n21.html
From: Robert D. Silverman
Jim Roth
Date: Thu, 23 May 1991 01:49:49 GMT
Subject: D. H. Lehmer
It is with a very great deal of sadness that I must report that D. H. Lehmer
passed away last night.
I am deeply saddened by this loss as Professor Lehmer's work has been a
source of personal inspiration for me. I consider him to be the father
of computational number theory; my major field of interest.
Bob Silverman
Mitre Corporation
Professor Lehmer worked on (among other things) the solution of sets of linear
Diophantine equations via Chinese Remainder Theorem. This involved building
a special-purpose computer which had many "delay lines" (recirculating loops)
of prime-integer length. When the numbers in all of the loops lined up (as in
a Las Vegas slot machine hitting a jackpot) a bell would ring and the data
would be dumped and printed out, then re-loaded into the loops. The first of
these machines was purely mechanical; later on (1965?) he bought surplus
radar delay lines and worked out a purely electronic number-theory machine
along the above lines, which he talked about at UCLA. He claimed that his
technique got answers hundreds of times faster than an IBM 704 would have.
Does anyone know whether he ever got a special VLSI chip built for
such purposes?
David L. Elliott
Washington University
There is a photograph and explanation of Dr. Lehmer's factoring machine
in the Dover book "Recreations in the Theory of Numbers" by Albert Beiler.
This machine had many gear driven wheels which would be halted when sets of
holes in them lined up, triggered by a photocell. It was called a
photoelectric number sieve.
Apparently it was an amazing, though tempermental, device, and was
inadvertantly "jammed" by a local Ham radio operator whose transmissions
triggered the photocell at times.
The book also mentions Lehmer's first factoring machine - a bicycle
sprocket and chain contraption!
Will future generations look back similarly at our current massively
parallel computers doing quantum chromodynamics calculations?
Jim Roth
Digital Equipment Corporation
|
from Mike Albaugh, Nov 22, 2017, talking about an end of life IBM computer at Berkeley, CA
... I was told that while the 7094 (7090?) had been purchased, all the
peripherals (and presumably the 7044) had been rented. That was the
explanation I was given for the "brain in a bucket" still being in
the computer center, where its one user was D.H. Lehmer.
Operators
described to me how he and his wife would come in and "play a
console duet" on the address and data switches, entering the code
for some long-running mathematical exploration. He would come back
days (weeks?) later and read the results from core.
When he relinquished
the machine, the Cal Computer Club was asked if we were interested,
and an IBM CE was asked for his opinion of its condition. His report
was that "someone" (Lehmer?) had apparently not been interested
in floating point or IO, so had scrounged SMS cards to keep the
integer stuff running. It was declared hopeless.
-Mike
|
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Updated May 15, 2017