LEO (1950)

Rod Smallwood RodSmallwood at mail.ediconsulting.co.uk
Thu Jul 19 13:47:30 CDT 2007

Amongst other references I found this

In 1951 the LEO I computer was operational and ran the world's first
regular routine office computer job.

 About the "Lyons Electronic Office" (LEO I)

The LEO I used 5,936 valves, plus another 300-400 in auxiliary
equipment. The LEO used 64 mercury tubes for storage (twice the memory
capacity of the EDSAC machine built in Cambridge). Each memory tube was
5 feet, four inches in length and weighed half a ton. The computer was
controlled from a control panel, with several oscilloscopes set up to
monitor contents of the storage area. The machine also had a speaker
installed and programmers could hear the sounds generated as LEO
performed certain calculations. The programmers became so accustomed to
certain frequency variations, that they could detect something was wrong
with a program by the sounds produced through the speaker. The
programmers also used this speaker arrangement to generate some of the
first "computer music."


-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Roger Holmes
Sent: 18 July 2007 14:24
To: cctalk at classiccmp.org
Subject: Re: LEO (1950)

> Date: Tue, 17 Jul 2007 20:43:50 +0100
> From: "Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk>
> I happened on the program by chance. It might have been called 
> Disappearing Britain. A lot of it was contemporaneous and could have 
> been a Lyons publicity film. (or at least bits of one). I suspect our 
> friends at the National Film Archive might know.

I suspect it is a contemporary promotional film on the Leo II dated
1957 and mentions that it has been working since 1953 - referring to Leo
1 I think, it is black and white and if that's it, I have it on a DVD
published by Buzz KnowledgeWorks which I bought on eBay.

> I inadvertently made an ambiguous statement. By commercial I meant its

> use, not its availability for sale.

I knew what you meant. Most early designs were one or two off scientific
machines, price no object.

> Where would you start to design such a thing? Valves yes.. 12AT7 
> Bistables as binary counters. Neon devices such as dekatrons as 
> decimal counters. RVL (Resistor Valve Logic). Storage = Ferrite Cores,

> Tape, Drum possibly.

I'm not sure many commercial machines were made with valves logic and a
main memory of core. Transistors and core main memory often came in
together. The ICT1200 series (AKA Hollerrith Electronic Computer) was
drum main memory and valves but its replacement the ICT1300 series used
"high speed switching transistors" and core memory with backing store of
drum and optionally tape.

> I once saw a Univac FAST RAN Drum memory. What a lump!!!

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