[CSL Colloq] The Architecture of Colossus, the first PC * 4:15PM, Wed February 04, 2003 in Gates B03 (fwd)

Sean McGrath sean at manybits.net
Fri Jan 30 08:27:02 EST 2004

[Note: Webcasts available live and from archives]

---------- Forwarded message ----------
Date: Fri, 30 Jan 2004 00:23:31 -0800
From: allison at stanford.edu
Reply-To: ee380 at shasta.stanford.edu
To: sean at manybits.net
Subject: [CSL Colloq] The Architecture of Colossus, the first PC * 4:15PM,
     Wed February 04, 2003 in Gates B03

               4:15PM, Wednesday, February 04, 2003
       NEC Auditorium, Gates Computer Science Building B03

Topic:    The Architecture of Colossus, the first PC

Speaker:  Benjamin Wells
          University of San Francisco

About the talk:

Colossus, the first electronic digital computer, was built by
Tommy Flowers at the General Post Office Research Station in
Dollis Hill, London. It was installed during December 1943 at
Bletchley Park, the famous WWII British code-cracking enclave.
Its purpose was to assist with the decryption of wireless traffic
among German high-level commands encrypted using the Lorenz
teletype cipher machine. Called Colossus because of its size, it
could be run by a single operator --and often was. At least in
that sense, it was also the world's first personal computer.

Bletchley had already developed a highly successful automated
attack on the Enigma cipher system under the guidance and genius
of Alan Turing. Built without direct input from Turing, Colossus
was designed to support the cracking of the highest volume of
German strategic code transmissions. These intelligence-rich
messages were thousands of characters long, overshadowing the
hand-encoded tactical traffic using Enigma. Because Colossus was
kept secret until 1973, and full details of its use and
construction were not released until 2000, it did not play a
direct role in the evolution of digital computers. Of course,
many who worked on it were involved with later computers.

With the release of previously classified documents, interest in
Colossus has grown over the last three years. This accessible,
multimedia talk will compare the architectural features of
Colossus with those of modern PCs. Although it is tempting to
assert that the former was a stored-program general purpose
machine, as some have done in print, that analysis is less than
promising. What is amazing is that Colossus introduced buffered
I/O, branch decisions, biquinary representation, and bit masking,
and anticipated some deeper modern features: parallelism, dual
rail, hardware interrupt, shift register, asynchronous dataflow,
and plug-ins. Moreover, recent results (AMS Abstracts 04T-68-2)
show that a universal Turing machine could have been implemented
on a cluster of the ten Colossi, proving the power of Colossus.

About the speaker:

Benjamin Wells teaches both mathematics and computer science
courses at the University of San Francisco, including freshman
seminars that combine science and art. He holds degrees from MIT
and UC Berkeley and has studied in four countries. The last
student of noted logician Alfred Tarski, Wells works on the
boundary of logic, algebra, and computing; he also contributes to
computer graphics and visual communication. He won a John
Templeton Foundation science and religion course prize in 1998
and held the USF Davies Professorship in 1989. He enjoys
mysticism, cooking, computer-supported art, hiking, languages,
dancing, tales, and family.

Contact information:

Benjamin Wells
Professor of Mathematics and Computer Science
University of San Francisco
wells at usfca.edu[2]

Embedded Links:
[ 1 ]    http://ee380.stanford.edu
[ 2 ]    mailto:wells at usfca.edu

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