The Old Pocklingtonian Old Pocklingtonian 2017-18 - Page 17
COMPUTER DESIGNER DIGBY
The OP office was recently contacted by Steven Kay,
the curator of a large early transistor computer, which
is held in the collection of The National Museum
of Computing (TNMoC) at Bletchley Park, Milton
Keynes. The computer is the Marconi Transistorised
Automatic Computer (TAC) designed by a
gentleman called Digby Worthy at the Marconi R&D
Department at Great Baddow, near Chelmsford,
Essex between 1959 and 1960. Steven wanted to
know if this was the same Digby Worthy in an article
he read, who, as a 15-year-old pupil at Pocklington
School, designed and built a Differential Analyser (an
early form of mechanical analogue computer) from
Meccano in around 1939. From what we can gather
they are indeed the same person!
Looking back through the archives, we discovered
that the Meccano Differential Analyser model that
Digby built at school was exhibited by the English
Electric Company. In reports, it is hailed as being
remarkable for its simplicity with a system of belts
and pulleys allowing the system to be constructed
with only a handful of parts.
Digby’s Marconi TAC as it is known, is a second-
generation computer based on germanium alloy
junction transistor technology. It was designed
in 1959-1960 in response to a requirement for a
computer to be used for real-time processing of
RADAR information for an early warning system
for the Swedish government. Later, two more were
made for use at the Nuclear Power Station at Wylfa
in North Wales running non-stop from 1968 to
2004. As far as we know, only five of this type of
computer were ever produced and only the two
from Wylfa survive. One is in TNMoC and the other
is in the Jim Austin private computer collection
near York. The one at TNMoC still works so Digby’s
design has stood the test of time!
As well as designing computers, it seems Digby
was quite a character. According to legend, while
he was a student, he found that introducing a little
condensed milk into the inner tubes of his bicycle
tyres meant that they would be self-healing in the
case of a puncture!
TAC in situ at Wylfa circa 1970.
(Sources: The Meccano Set Computers: A history
of differential analyzers made from children’s
toys, Robinson T., IEEE Control Systems Magazine,
June 2005; The Marconi Transistorised Automatic
Computer (“TAC”). Kay S., TNMoC, photo: TNMoC
1. This looks like the base of a trophy, but what was it awarded for? Do you know anything about it?
2. Does anyone recognise this banner? Do you know anything about it and how the school came to have it?
3. Does anyone know anything about this blazer? Is it a school blazer or an OP blazer and what was it for?
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Here is the information we have come up with for last year’s
‘Down Memory Lane’ photos. The pupil in the school uniform
pictured with the cricket team in photo 1 is the current OP
President, Trevor Loten (70-80)! There were no responses for
photo 2 unfortunately.
For photo 3, we are pretty sure this is the 1975-76 under 12 B
team. Thanks to Steve Baker and Jonathan Loney for their help
with names as follows:
Back row (L-R): Tim Baier, Paul Reaston, Michael Wardle,
J.Smith?, Steve Baker, John Skinner, Steve Chick / somebody
Digby, R.Clark?, D.Wynn, C.Davey?, Mark Currey
Front row (L-R): Gary Haigh, Stuart Tragheim, Tim Dowling,
Jonathan Loney, Russell Gardner, C.Anderson?, Andy Ramshaw