Celebrating Jean Bartik – she was one of six women who programmed the ‘ENIAC’, a computer from the 1940s

Four of the 42 panels that made up ENIAC.

by Jo Brodie, Queen Mary University of London.

Jean Bartik (born Betty Jean Jennings) was one of six women who programmed “ENIAC” (the Electronic Numerical Integrator and Computer), one of the earliest electronic programmable computers. The work she and her colleagues did in the 1940s had a huge impact on computer science however their contribution went largely unrecognised for 40 years. 

Jean Bartik – born 27 December 1924; died on this day, 23 March 2011

Born in Missouri USA in December 1924 to a family of teachers in Betty (as she was then known) showed promise in Mathematics, graduating from her high school in the summer of 1941 aged 16 with the highest marks in maths ever seen at her school. She began her degree in Maths and English at her local teachers’ college (which is now Northwest Missouri State University) but everything changed dramatically a few months in when the US became involved in the Second World War. The men (teachers and students) were called up for war service leaving a dwindling department and her studies were paused, resuming only in 1943 when retired professors were brought in to teach; she graduated in January 1945, the only person in her year to graduate in Maths.

Although her family encouraged her to become a local maths teacher she decided to seek more distant adventures. The University of Pennsylvania in Philadelphia (~1,000 miles away) had put out a call for people with maths skills to help with the war effort, she applied and was accepted. Along with over 80 other women she was employed to calculate, using advanced maths including differential calculus equations, accurate trajectories of bullets and bombs (ballistics) for the military. She and her colleagues were ‘human computers’ (people who did calculations before the word meant what it does today) creating range tables, columns of information that told the US army where they should point their guns to be sure of hitting their targets. This was complex work that had to take account of weather conditions as well as more obvious things like distance and size of the gun barrel.

Even with 80-100 women working on every possible combination of gun size and angle it still took over a week to generate one data table so the US Army was obviously keen to speed things up as much as possible. They had previously given funding in 1943 to John Mauchly (a physicist) and John Presper Eckert (an electrical engineer) to build a programmable electronic calculator – ENIAC – which would automate the calculations and give them a huge speed advantage. By 1945 the enormous new machine, which took up a room (as computers tended to do in those days) consisted of several thousand vacuum tubes, weighed 30 tonnes and was held together with several million soldered joints. It would be programmed with punched cards with holes punched at different positions in each card allowing a current to pass (or not pass, if no hole present) through a particular set of cables connected through a plugboard (like old-fashioned telephone exchanges). 

From the now 100 women working as human computers in the department six were selected to become the machine’s operators – a role that was exceptional. There were no manuals available and ‘programming’, as we know it today, didn’t yet exist – it was much more physical. Not only did the ‘ENIAC six’ have to correctly wire each cable they had to fully understand the machine’s underlying blueprints and electronic circuits to make it work as expected. Repairs could involve crawling into the machine to fix a broken wire or vacuum tube. 

Two of the ENIAC programmers, are preparing the computer for Demonstration Day in February 1946. “U.S. Army Photo” from the archives of the ARL Technical Library. Left: Betty Jennings (later Bartik), right: Frances Bilas (Spence) – via Wikipedia.

World War 2 actually ended in September 1945 before ENIAC was brought into full service, but being programmable (which meant rewiring the cables) it would soon be put to other uses. Jean really enjoyed her time working on ENIAC and said later that she’d “never since been in as exciting an environment. We knew we were pushing back frontiers” but she was working at a time when men’s jobs and achievements were given more credit than women’s.

In February 1946 ENIAC was unveiled to the press with its (male) inventors demonstrating its impressive calculating speeds and how much time could be saved compared with people performing the calculations with mechanical desk calculators. While Jean and some of the other women were in attendance (and appear in press photographs of the time) the women were not introduced, their work wasn’t celebrated, they were not always correctly identified in the photographs and were even not invited to the celebratory dinner after the event – as Jean said in a later interview (see the second video (YouTube) below) “We were sort of horrified!”.

In December 1946 she married William Bartik (an engineer) and over the next few years was instrumental in the programming and development of other early computers. She also taught others how to program them (an early computer science teacher!). She often worked with her husband too, following him to different cities for work. However her husband took on a new role in 1951 and the company’s policy was that wives were not allowed to work in the same place. Frustrated, Jean left computing for a while and also took a career break to raise her family. 

In the late 1960s she returned to the field of computer science and for several years she blended her background in Maths and English, writing technical reports on the newer ‘minicomputers’ (still quite large compared to modern computers but you could fit more of them in a room). However the company she worked for was sold off and she was made redundant in 1985 at the age of 60. She couldn’t find another job in the industry which she put down to age discrimination and she spent her remaining career working in real estate (selling property or land). She died, aged 86 on 23 March 2011. 

Jean’s contribution to computer science remained largely unknown to the wider world until 1986 when Kathy Kleinman (an author, law professor and programmer) decided to find out who the women in these photographs were and rediscovered the pioneering work of the ENIAC six.

Vimeo trailer for Kathy Kleinman’s book and documentary
YouTube video from the Computer History Museum

The ENIAC six women were Kathleen McNulty Mauchly Antonelli, Jean Jennings Bartik, Frances (Betty) Snyder Holberton, Marlyn Wescoff Meltzer, Frances Bilas Spence, and Ruth Lichterman Teitelbaum.

Further reading

Jean Bartik (Wikipedia)
ENIAC (Wikipedia)
The ENIAC Programmers Project – Kathy Kleinman’s project which uncovered the women’s role
Betty Jean Jennings Bartik (biography by the University of St Andrews)

Adapted (text added) version of Woman at a computer image by Chen from Pixabay

This blog is funded through EPSRC grant EP/W033615/1.

Inspiring Wendy Hall

Woman's manicured hand pointing a remote control at a large screen television on the opposite wall in a spacious modern room with white minimal furnishing.

by Paul Curzon, Queen Mary University of London

This article is inspired by a keynote talk Wendy Hall gave at the ITiCSE conference in Madrid, 2008.

What inspires researchers to dedicate their lives to study one area? In the case of computer scientist Dame Wendy Hall it was a TV programme called Hyperland starring former Dr Who Tom Baker and writer Douglas Adams of Hitchhiker’s Guide to the Galaxy fame that inspired her to become one of the most influential researchers of her area.

Woman's manicured hand pointing a remote control at a large screen television on the opposite wall in a spacious modern room with white minimal furnishing.
Remote control TV image by mohamed_hassan from Pixabay

A pioneer and visionary in the area of web science, many of Dame Wendy’s ideas have started to appear in the next generation web: the ‘great web that is yet to come’ (as Douglas Adams might put it), otherwise known as the semantic web. She has stacked up a whole bunch of accolades for her work. She is a Professor at the University of Southampton, a former President of the British Computer Society and now the first non-US President of the most influential body in computer science, the Association for Computing Machinery. She is also a Fellow of the Royal Academy of Engineering and this year she topped it all and gaining her most impressive sounding title for sure by being made a Dame Commander of the British Empire.

So how did that TV programme set her going?

Douglas Adams and Tom Baker acted out a vision of the future, a vision of how TV was going to change. At the time the web didn’t exist and TV was just something you sat in front of and passively watched. The future they imagined was interactive TV. TV that was personal. TV that did more than just entertain but served all your information needs.

In the programme Douglas Adams was watching TV, vegetating in front of it…and then Tom Baker appeared on Douglas’s screen. He started asking him questions…and then he stepped out of the TV screen. He introduced himself as a software agent, someone who had all the information ever put into digital format at his fingertips. More than that he was Douglas’s personal agent. He would use that information to answer any questions Douglas had. Not just to bring back documents (Google-style) that had something to do with the question and leave you to work out what to do with it all, but actually answer the question. He was an agent that was servant and friend, an agent whose character could even be changed to fit his master’s mood.

Wendy was inspired…so inspired that she decided she was going to make that improbable vision a reality. Reality hasn’t quite caught up yet, but she is getting there.

Most people who think about it at all believe that Tim Berners-Lee invented the idea of the web and of hypertext, the links that connect web pages together. He was the one that kick-started it into being a global reality, making it happen, but actually lots of people had been working in research labs round the world on the same ideas for years before, Wendy included, with her Microcosm hypermedia system. Tim’s version of hypermedia – interactive information – was a simple version, one simple enough to get the idea off the ground. Its time is coming to an end now though.

What is coming next? The semantic web: and it will be much more powerful. It is a version of the web much closer to that TV program, a version where the web’s data is not just linked to other data but where words, images, pictures, videos are all tagged with meaning: tags that the software agents of the future can use to understand.

The structure is now there for it to happen. What is needed is for people to start to use it, to write their web pages that way, to actually make it everyday reality. Then the web programmers will be able to start innovating with new ideas, new applications that use it, and the web scientists like Wendy will be able to study it: to work out what works for people, what doesn’t and why.

Then maybe it’s your turn to be inspired and drive the next leap forward.

This article was originally published on the CS4FN website.

Adapted (text added) version of Woman at a computer image by Chen from Pixabay

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This blog is funded through EPSRC grant EP/W033615/1.

Alan Turing’s life

by Jonathan Black, Paul Curzon and Peter W. McOwan, Queen Mary University of London

From the archive

Alan Turing smiling

Alan Turing was born in London on 23 June 1912. His parents were both from successful, well-to-do families, which in the early part of the 20th century in England meant that his childhood was pretty stuffy. He didn’t see his parents much, wasn’t encouraged to be creative, and certainly wasn’t encouraged in his interest in science. But even early in his life, science was what he loved to do. He kept up his interest while he was away at boarding school, even though his teachers thought it was beneath well-bred students. When he was 16 he met a boy called Christopher Morcom who was also very interested in science. Christopher became Alan’s best friend, and probably his first big crush. When Christopher died suddenly a couple of years later, Alan partly helped deal with his grief with science, by studying whether the mind was made of matter, and where – if anywhere – the mind went when someone died.

The Turing machine

After he finished school, Alan went to the University of Cambridge to study mathematics, which brought him closer to questions about logic and calculation (and mind). After he graduated he stayed at Cambridge as a fellow, and started working on a problem that had been giving mathematicians headaches: whether it was possible to determine in advance if a particular mathematical proposition was provable. Alan solved it (the answer was no), but it was the way he solved it that helped change the world. He imagined a machine that could move symbols around on a paper tape to calculate answers. It would be like a mind, said Alan, only mechanical. You could give it a set of instructions to follow, the machine would move the symbols around and you would have your answer. This imaginary machine came to be called a Turing machine, and it forms the basis of how modern computers work.

Code-breaking at Bletchley Park

By the time the Second World War came round, Alan was a successful mathematician who’d spent time working with the greatest minds in his field. The British government needed mathematicians to help them crack the German codes so they could read their secret communiqués. Alan had been helping them on and off already, but when war broke out he moved to the British code-breaking headquarters at Bletchley Park to work full-time. Based on work by Polish mathematicians, he helped crack one of the Germans’ most baffling codes, called the Enigma, by designing a machine (based on earlier version by the Poles again!) that could help break Enigma messages as long as you could guess a small bit of the text (see box). With the help of British intelligence that guesswork was possible, so Alan and his team began regularly deciphering messages from ships and U-boats. As the war went on the codes got harder, but Alan and his colleagues at Bletchley designed even more impressive machines. They brought in telephone engineers to help marry Alan’s ideas about logic and statistics with electronic circuitry. That combination was about to produce the modern world.

Building a brain

The problem was that the engineers and code-breakers were still having to make a new machine for every job they wanted it to do. But Alan still had his idea for the Turing machine, which could do any calculation as long as you gave it different instructions. By the end of the war Alan was ready to have a go at building a Turing machine in real life. If it all went to plan, it would be the first modern electronic computer, but Alan thought of it as “building a brain”. Others were interested in building a brain, though, and soon there were teams elsewhere in the UK and the USA in the race too. Eventually a group in Manchester made Alan’s ideas a reality.

Troubled times

Not long after, he went to work at Manchester himself. He started thinking about new and different questions, like whether machines could be intelligent, and how plants and animals get their shape. But before he had much of a chance to explore these interests, Alan was arrested. In the 1950s, gay sex was illegal in the UK, and the police had discovered Alan’s relationship with a man. Alan didn’t hide his sexuality from his friends, and at his trial Alan never denied that he had relationships with men. He simply said that he didn’t see what was wrong with it. He was convicted, and forced to take hormone injections for a year as a form of chemical castration.

Although he had had a very rough period in his life, he kept living as well as possible, becoming closer to his friends, going on holiday and continuing his work in biology and physics. Then, in June 1954, his cleaner found him dead in his bed, with a half-eaten, cyanide-laced apple beside him.

Alan’s suicide was a tragic, unjust end to a life that made so much of the future possible.

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cs4fn issue 14 cover

This blog is funded through EPSRC grant EP/W033615/1.

Daphne Oram: the dawn of music humans can’t play

by Paul Curzon, Queen Mary University of London

Music notes over paint brush patterns
Image by Gerd Altmann from Pixabay

What links James Bond, a classic 1950s radio comedy series and a machine for creating music by drawing? … Electronic music pioneer: Daphne Oram.

Oram was one of the earliest musicians to experiment with electronic music, and was the first woman to create an electronic instrument. She realised that the advent of electronic music meant composers no longer had to worry about whether anyone could actual physically perform the music they composed. If you could write it down in a machine readable way then machines could play it electronically. That idea opened up whole new sounds and forms of music and is an idea that pop stars and music producers still make use of today.

She learnt to play music as a child and was good enough to be offered a place at the Royal College of Music, though turned it down. She also played with radio electronics with her brothers, creating radio gadgets and broadcasting music from one room to another. Combining music with electronics became her passion and she joined the BBC as a sound engineer. This was during World War 2 and her job included being the person ready during a live music broadcast to swap in a recording at just the right point if, for example, there was an air raid that meant the performance had to be abandoned. The show, after all, had to go on.

Composing electronic music

She went on to take this idea of combining an electronic recording with live performance further and composed a novel piece of music called Still Point that fully combined orchestral with electronic music in a completely novel way. The BBC turned down the idea of broadcasting it, however, so it was not played for 70 years until it was rediscovered after her death, ultimately being played at a BBC Prom.

Composers no longer had to worry
about whether anyone could actually
physically perform the music they composed

She started instead to compose electronic music and sounds for radio shows for the BBC which is where the comedy series link came in. She created sound effects for a sketch for the Goon Show (the show which made the names of comics including Spike Milligan and Peter Sellers). She constantly played with new techniques. Years later it became standard for pop musicians to mess with tapes of music to get interesting effects, speeding them up and down, rerecording fragments, creating loops, running tapes backwards, and so on. These kinds of effects were part of amazing sounds of the Beatles, for example. Oram was one of the first to experiment with these kinds of effects and use them in her compositions – long before pop star producers.

One of the most influential things she did was set up the BBC Radiophonic Workshop which went on to revolutionise the way sound effects and scores for films and shows were created. Oram though left the BBC shortly after it was founded, leaving the way open for other BBC pioneers like Delia Derbyshire. Oram felt she wasn’t getting credit for her work, and couldn’t push forward with some of her ideas. Instead Oram set herself up as an independent composer, creating effects for films and theatre. One of her contracts involved creating electronic music that was used on the soundtracks of the early Bond films starring Sean Connery – so Shirley Bassey is not the only woman to contribute to the Bond sound!

The Music Machine

While her film work brought in the money, she continued with her real passion which was to create a completely new and highly versatile way to create music…by drawing. She built a machine – the Oramics Machine – that read a composition drawn onto film reels. It fulfilled her idea of having a machine that could play anything she could compose (and fulfilled a thought she had as a child when she wondered how you could play the notes that fell between the keys on a piano!).

Image by unknown photographer from wikimedia.

The 35mm film that was the basis of her system that dates all the way back to the 19th century when George Eastman, Thomas Edison and Kennedy Dixon pioneered the invention film based photography and then movies. It involved a light sensitive layer being painted on strips of film with holes down the side that allowed the film to be advanced. This gave Oram a recording media. She could etch or paint subtle shapes and patterns on to the film. In a movie light was shone through the film, projecting the pictures on the film on to the screen. Oram instead used light sensors to detect the patterns on the film and convert it to electronic signals. Electronic circuitry she designed (and was awarded patents for) controlled cathode ray tubes that showed the original drawn patterns but now as electrical signals. Ultimately these electrical signals drove speakers. Key to the flexibility of the system was that different aspects of the music were controlled by patterns on different films. One for example controlled the frequency of the sound, others the timbre or tone quality and others the volume. These different control signals for the music were then combined by Oram’s circuitry. The result of combining the fine control of the drawings with the multiple tapes meant she had created a music machine far more flexible in the sound it could produce than any traditional instrument or orchestra. Modern music production facilities use very similar approaches today though based on software systems rather than the 1960s technology available to Oram.

Ultimately, Daphne Oram was ahead of her time as a result of combining her two childhood fascinations of music and electronics in a way that had not been done before. She may not be as famous as the great record producers who followed her, but they owe a lot to her ideas and innovation.

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EPSRC supports this blog through research grant EP/W033615/1. 

Gary Starkweather (b 9 Jan 1938) invented the laser printer and colour management

Gary Starkweather (9 January 1938 – 26 December 2019) invented and developed the first laser printer. In the late 1960s he was an engineer, with a background in optics, working in the US for the Xerox company (famous for their photocopiers) and came up with the idea of using a laser beam to transfer the image to the photocopier (so that it could make lots of copies), speeding up the process of printing documents.

Printer image by David Dunmore from Pixabay

You can hear what a modern laser printer sounds like by clicking on the link below…

…and there’s a video of him talking about the ‘Eureka moment’ of his invention here.

Laser printers are found in offices worldwide – you may even have one at home.

Colour wheel image by Pete Linforth from Pixabay

He also invented colour management which is a way of ensuring that a shade of blue colour on your computer’s or phone’s screen looks the same on a TV screen or when printed out. Different devices have different display colours so ‘red’ on one device might not be the same as ‘red’ on another. Colour management is something that happens in devices behind the scenes and which translates the colour instruction from one device to produce the closest match on another. There is an International Color Consortium (ICC) which helps different device manufacturers ensure that colour is “seamless between devices and documents”.

Starkweather also received an Academy Award (also known as an Oscar) for Technical Achievement in 1994, for the work he’d done in colour film scanning. That involves taking a strip of film and converting it digitally so it can be edited on a computer.

Also on this day, in 2007, the first Apple iPhone was announced (though not available until June that year)… and all iPhones use colour management!

Hidden Figures: NASA’s brilliant calculators #BlackHistoryMonth

Full Moon and silhouetted tree tops

by Paul Curzon, Queen Mary University of London

Full Moon with a blue filter
Full Moon image by PIRO from Pixabay

NASA Langley was the birthplace of the U.S. space program where astronauts like Neil Armstrong learned to land on the moon. Everyone knows the names of astronauts, but behind the scenes a group of African-American women were vital to the space program: Katherine Johnson, Mary Jackson and Dorothy Vaughan. Before electronic computers were invented ‘computers’ were just people who did calculations and that’s where they started out, as part of a segregated team of mathematicians. Dorothy Vaughan became the first African-American woman to supervise staff there and helped make the transition from human to electronic computers by teaching herself and her staff how to program in the early programming language, FORTRAN.

FORTRAN code on a punched card, from Wikipedia.

The women switched from being the computers to programming them. These hidden women helped put the first American, John Glenn, in orbit, and over many years worked on calculations like the trajectories of spacecraft and their launch windows (the small period of time when a rocket must be launched if it is to get to its target). These complex calculations had to be correct. If they got them wrong, the mistakes could ruin a mission, putting the lives of the astronauts at risk. Get them right, as they did, and the result was a giant leap for humankind.

See the film ‘Hidden Figures’ for more of their story (trailer below).

This story was originally published on the CS4FN website and was also published in issue 23, The Women Are (Still) Here, on p21 (see ‘Related magazine’ below).

See more in ‘Celebrating Diversity in Computing

We have free posters to download and some information about the different people who’ve helped make modern computing what it is today.

Screenshot showing the vibrant blue posters on the left and the muted sepia-toned posters on the right

Or click here: Celebrating diversity in computing

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This blog is funded through EPSRC grant EP/W033615/1.

Writing together: Clarence ‘Skip’ Ellis #BlackHistoryMonth

Small photo of Clarence 'Skip' Ellis

by Paul Curzon, Queen Mary University of London

Small photo of Clarence 'Skip' Ellis
Small photo of
Clarence ‘Skip’ Ellis

Back in 1956, Clarence Ellis started his career at the very bottom of the computer industry. He was given a job, at the age of 15, as a “computer operator” … because he was the only applicant. He was also told that under no circumstances should he touch the computer! Its lucky for all of us he got the job, though! He went on to develop ideas that have made computers easier for everyone to use. Working at a computer was once a lonely endeavour: one person, on one computer, doing one job. Clarence Ellis changed that. He pioneered ways for people to use computers together effectively.

The graveyard shift

The company Clarence first worked for had a new computer. Just like all computers back then, it was the size of a room. He worked the graveyard shift and his duties were more those of a nightwatchman than a computer operator. It could have been a dead-end job, but it gave him lots of spare time and, more importantly, access to all the computer’s manuals … so he read them … over and over again. He didn’t need to touch the computer to learn how to use it!

Saving the day

His studying paid dividends. Only a few months after he started, the company had a potential disaster on its hands. They ran out of punch cards. Back then punch cards were used to store both data. They used patterns of holes and non-holes as a way to store numbers as binary in a away a computer could read them. Without punchcards the computer could not work!

It had to though, because the payroll program had to run before the night was out. If it didn’t then no-one would be paid that month. Because he had studied the manuals in detail, and more so than anyone else, Clarence was the only person who could work out how to reuse old punch cards. The problem was that the computer used a system called ‘parity checking’ to spot mistakes. In its simplest form parity checking of a punch card involves adding an extra binary digit (an extra hole or no-hole) on the end of each number. This is done in a way that ensures that the number of holes is even. If there is an even number of holes already, the extra digit is left as a non-hole. If, on the other hand there is an odd number of holes, a hole is punched as the extra digit. That extra binary digit isn’t part of the number. It’s just there so the computer can check if the number has been corrupted. If a hole was accidentally or otherwise turned into a non-hole (or vice versa), then this would show up. It would mean there was now an odd number of holes. Special circuitry in the computer would spot this and spit out the card, rejecting it. Clarence knew how to switch that circuitry off. That meant they could change the numbers on the cards by adding new holes without them being rejected.

After that success he was allowed to become a real operator and was relied on to troubleshoot whenever there were problems. His career was up and running.

Clicking icons

He later worked at Xerox Parc, a massively influential research centre. He was part of the team that invented graphical user interfaces (GUIs). With GUIs Xerox Parc completely transformed the way we used computers. Instead of typing obscure and hard to remember commands, they introduced the now standard ideas, of windows, icons, dragging and dropping, using a mouse, and more. Clarence, himself, has been credited with inventing the idea of clicking on an icon to run a program.

Writing Together

As if that wasn’t enough of an impact, he went on to help make groupware a reality: software that supports people working together. His focus was on software that let people write a document together. With Simon Gibbs he developed a crucial algorithm called Operational Transformation. It allows people to edit the same document at the same time without it becoming hopelessly muddled. This is actually very challenging. You have to ensure that two (or more) people can change the text at exactly the same time, and even at the same place, without each ending up with a different version of the document.

The actual document sits on a server computer. It must make sure that its copy is always the same as the ones everyone is individually editing. When people type changes into their local copy, the master is sent messages informing it of the actions they performed. The trouble is the order that those messages arrive can change what happens. Clarence’s operational transformation algorithm solved this by changing the commands from each person into ones that work consistently whatever order they are applied. It is the transformed operation that is the one that is applied to the master. That master version is the version everyone then sees as their local copy. Ultimately everyone sees the same version. This algorithm is at the core of programs like Google Docs that have ensured collaborative editing of documents is now commonplace.

Clarence Ellis started his career with a lonely job. By the end of his career he had helped ensure that writing on a computer at least no longer needs to be a lonely affair.

This article was originally published on the CS4FN website. One of the aims of our Diversity in Computing posters (see below) is to help a classroom of young people see the range of computer scientists which includes people who look like them and people who don’t look like them. You can download our posters free from the link below.

See more in ‘Celebrating Diversity in Computing

We have free posters to download and some information about the different people who’ve helped make modern computing what it is today.

Screenshot showing the vibrant blue posters on the left and the muted sepia-toned posters on the right

Or click here: Celebrating diversity in computing

This blog is funded through EPSRC grant EP/W033615/1.

CS4FN Advent – Day 25: Merry Christmas! Today’s post is about the ‘wood computer’

Today is the final post in our CS4FN Christmas Computing Advent Calendar – it’s been a lot of fun rummaging in the CS4FN back catalogue, and also finding out about some new things to write about.

Each day we published a blog post about computing with the theme suggested by the picture on the advent calendar’s ‘door’. Our first picture was a woolly jumper so the accompanying post was about the links between knitting and coding, the door with a picture of a ‘pair of mittens’ on led to a post about pair programming and gestural gloves, a patterned bauble to an article about printed circuit boards, and so on. It was fun coming up with ideas and links and we hope it was fun to read too.

We hope you enjoyed the series of posts (scroll to the end to see them all) and that you have a very Merry Christmas. Don’t forget that if you’re awake and reading this at the time it’s published (6.30am Christmas Day) and it’s not cloudy, you may be able to see Father Christmas passing overhead at 6.48am. He’s just behind the International Space Station…

And on to today’s post which is accompanied by a picture of a Christmas Tree, so it’ll be a fairly botanically-themed post. The suggestion for this post came from Prof Ursula Martin of Oxford University, who told us about the ‘wood computer’.

It’s a Christmas tree!

The Wood Computer

by Jo Brodie, QMUL.

Other than asking someone “do you know what this tree is?” as you’re out enjoying a nice walk and coming across an unfamiliar tree, the way of working out what that tree is would usually involve some sort of key, with a set of questions that help you distinguish between the different possibilities. You can see an example of the sorts of features you might want to consider in the Woodland Trust’s page on “How to identify trees“.

Depending on the time of year you might consider its leaves – do they have stalks or not, do they sit opposite from each other on a twig or are they diagonally placed etc. You can work your way through leaf colour, shape, number of lobes on the leaf and also answer questions about the bark and other features of your tree. Eventually you narrow things down to a handful of possibilities.

What happens if the tree is cut up into timber and your job is to check if you’re buying the right wood for your project. If you’re not a botanist the job is a little harder and you’d need to consider things like the pattern of the grain, the hardness, the colour and any scent from the tree’s oils.

Historically, one way of working out which piece of timber was in front of you was to use a ‘wood computer’ or wood identification kit. This was prepared (programmed!) from a series of index cards with various wood features printed on all the cards – there might be over 60 different features.

Every card had the same set of features on it and a hole punched next to every feature. You can see an example of a ‘blank’ card below, which has a row of regularly placed holes around the edge. This one happens to be being used as a library card rather than a wood computer (though if we consider what books are made of…).

Image of an edge-notched card (actually being used as a library card though), from Wikipedia.

I bet you can imagine inserting a thin knitting needle into any of those holes and lifting that card up – in fact that’s exactly how you’d use the wood computer. In the tweet below you can see several cards that made up the wood computer.

One card was for one tree or type of wood and the programmer would add notch the hole next to features that particularly defined that type. For example you’d notch ‘has apples’ for the apple tree card but leave it as an intact hole on the pear tree card.  If a particular type of timber had fine grained wood they’d add the notch to the hole next to “fine-grained”. The cards were known, not too surprisingly, as edge-notched cards.

You can see what one looks like here with some notches cut into it. You might have spotted how knitting needles can help you in telling different woods apart.

Holes and notches

Edge-notched card overlaid on black background, with two rows of holes. On the top a hole in the first row is notched, on the right hand side two holes are notched. Image from Wikipedia.

Each card would end up with a slightly different pattern of notched holes, and you’d end up with lots of cards that are slightly different from each other.

Example ‘wood computer’. At the end of your search (to find out which tree your piece of wood came from) you are left with two cards for fine-grained wood. If your sample has a strong scent then it’s likely it’s the tree in the card on the right (though you could arrive at the same conclusion by using the differences in colour too). The card at the top is the blank un-notched card.

How it works

Your wood computer is basically a stack of cards, all lined up and that knitting needle. You pick a feature that your tree or piece of wood has and put your needle through that hole, and lift. All of the cards that don’t have that feature notched will have an un-notched hole and will continue to hang from your knitting needle. All of the cards that contain wood that do have that feature have now been sorted from your pile of cards and are sitting on the table.

You can repeat the process several times to whittle (sorry!) your cards down by choosing a different feature to sort them on.

The advantage of the cards is that they are incredibly low tech, requiring no electricity or phone signal and they’re very easy to use without needing specialist botanical knowledge.

You can see a diagram of one on page 8 of the 20 page PDF “Indian Standard: Key for identification of commercial timbers”, from 1974.

Teachers: we have a classroom sorting activity that uses the same principles as the wood computer. Download our Punched Card Searching PDF from our activity page.

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

Previous Advent Calendar posts

CS4FN Advent – Day 23: Bonus material – see “Santa’s sleigh” flying overhead (23 December 2021) – this was an extra post so that people could get ready to see “Father Christmas” passing overhead on Christmas Day at 6:48am).

CS4FN Advent – Day 25: Merry Christmas! Today’s post is about the ‘wood computer’ (25 December 2021) – this post

CS4FN Advent – Day 22: stars and celestial navigation

Every day from the 1st to the 25th of December this blog will publish a Christmas Computing post, as part of our CS4FN Christmas Computing Advent Calendar. On the front of the calendar for each day is a festive cartoon which suggests the post’s theme – today’s is a star, so today’s post is about finding your way: navigation.

Follow that star…


In modern cities looking up at the night sky is perhaps not as dramatic as it might have been in the past, or in a place with less light pollution. For centuries people have used stars and the patterns they form to help them find their way.

GPS Orbital Navigator Satellite (DRAGONSat), photograph by NASA.

There are many ways our explorations of space have led to new technologies, though satellites have perhaps had the most obvious effect on our daily lives. Early uses were just for communication, allowing live news reports from the other side of the world, with networks that span the globe. More recently GPS – the Global Positioning System has led to new applications and now we generally just use our phones or satnav to point us in the right direction.


The very first computers

by Paul Curzon, QMUL. This post was first published on the CS4FN website.

Victorian engineer Charles Babbage designed, though never built the first mechanical computer. The first computers had actually existed for a long time before he had his idea, though. The British superiority at sea and ultimately the Empire was already dependent on them. They were used to calculate books of numbers that British sailors relied on to navigate the globe. The original meaning of the word computer was actually a person who did these calculations. The first computers were humans.

An American almanac from 1816. Image by Dave Esons from Pixabay

Babbage became interested in the idea of creating a mechanical computer in part because of computing work he did himself, calculating accurate versions of numbers needed for a special book: ‘The Nautical Almanac’. It was a book of astronomical tables, the result of an idea of Astronomer Royal, Nevil Maskelyne. It was the earliest way ships had to reliably work out their longitudinal (i.e., east-west) position at sea. Without them, to cross the Atlantic, you just set off and kept going until you hit land, just as Columbus did. The Nautical Almanac gave a way to work out how far west you were all the time.

Maskelyne’s idea was based on the fact that the angle from the moon’ to a person on the Earth and back to a star was the same at the same time wherever that person was looking from (as long as they could see both the star and moon at once). This angle was called the lunar distance.

The lunar distance could be used to work out where you were because as time passed its value changed but in a predictable way based on Newton’s Laws of motion applied to the planets. For a given place, Greenwich say, you could calculate what that lunar distance would be for different stars at any time in the future. This is essentially what the Almanac recorded.

Moon image by PollyDot from Pixabay

Now the time changes as you move East or West: Dawn gradually arrives later the further west you go, for example, as the Earth rotates the sun comes into view at different times round the planet). That is why we have different time zones. The time in the USA is hours behind that in Britain which itself is behind that in China. Now suppose you know your local time, which you can check regularly from the position of the sun or moon, and you know the lunar distance. You can look up in the Almanac the time in Greenwich that the lunar distance occurs and that gives you the current time in Greenwich. The greater the difference that time is to your local time, the further West (or East) you are. It is because Greenwich was used as the fixed point for working the lunar distances out, that we now use Greenwich Mean Time as UK time. The time in Greenwich was the one that mattered!

This was all wonderful. Sailors just had to take astronomical readings, do some fairly simple calculations and a look up in the Almanac to work out where they were. However, there was a big snag. it relied on all those numbers in the tables having been accurately calculated in advance. That took some serious computing power. Maskelyne therefore employed teams of human ‘computers’ across the country, paying them to do the calculations for him. These men and women were the first industrial computers.

Book of logarithms, image by sandid from Pixabay

Before pocket calculators were invented in the 1970s the easiest way to do calculations whether big multiplication, division, powers or square roots was to use logarithms (not to be confused with algorithm). The logarithm of a number is just the number of times you can divide it by 10 before you get to 1. Complicated calculations can be turned in to simple ones using logarithms. Therefore the equivalent of the pocket calculator was a book containing a table of logarithms. Log tables were the basis of all other calculations including maritime ones. Babbage himself became a human computer, doing calculations for the Nautical Almanac. He calculated the most accurate book of log tables then available for the British Admiralty.

The mechanical computer came about because Babbage was also interested in finding the most profitable ways to mechanise work in factories. He realised a machine could do more than weave cloth but might also do calculations. More to the point such a machine would be able to do them with a guaranteed accuracy, unlike people. He therefore spent his life designing and then trying to build such a machine. It was a revolutionary idea and while his design worked, the level of precision engineering needed was beyond what could be done. It was another hundred years before the first electronic computer was invented – again to replace human computers working in the national interest…but this time at Bletchley Park doing the calculations needed to crack the German military codes and so win the World War II.


The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.



Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)


CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)


CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)


CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)


CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)


CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)


CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021)


CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, black boxes and another computing puzzle (8 December 2021)


CS4FN Advent – Day 9: gingerbread man – computing and ‘food’ (cookies, spam!), and a puzzle (9 December 2021)


CS4FN Advent – Day 10: Holly, Ivy and Alexa – chatbots and the useful skill of file management. Plus win at noughts and crosses – (10 December 2021)


CS4FN Advent – Day 11: the proof of the pudding… mathematical proof (11 December 2021)


CS4FN Advent – Day 12: Computer Memory – Molecules and Memristors – (12 December 2021)


CS4FN Advent – Day 13: snowflakes – six-sided symmetry, hexahexaflexagons and finite state machines in computing (13 December 2021)


CS4FN Advent – Day 14 – Why is your internet so slow + a festive kriss-kross puzzle (14 December 2021)


CS4FN Advent – Day 15 – a candle: optical fibre, optical illusions (15 December 2021)


CS4FN Advent – Day 16: candy cane or walking aid: designing for everyone, human computer interaction (16 December 2021)


CS4FN Advent – Day 17: reindeer and pocket switching (17 December 2021)


CS4FN Advent – Day 18: cracker or hacker? Cyber security(18 December 2021)


CS4FN Advent – Day 19: jingle bells or warning bells? Avoiding computer scams (19 December 2021)


CS4FN Advent – Day 20: where’s it @? Gift tags and internet addresses (20 December 2021)


CS4FN Advent – Day 21: wreaths and rope memory – weave your own space age computer (21 December 2021)



CS4FN Advent – Day 22: stars and celestial navigation (22 December 2021) – this post




CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle

This post is behind the 5th ‘door’ of the CS4FN Christmas Computing Advent Calendar – we’re publishing a computing-themed (and sometimes festive-themed) post every day until Christmas Day. Today’s picture is a snowman, and what’s a snowman made of but frozen water?

1. You can make a computer out of water!

1n 1936 Vladimir Lukyanov got creative with some pipes and pumps built a computer, called a water (or hydraulic) integrator, which could store water temporarily in some bits and pump water to other bits. The movement of water and where it ended up used the ‘simplicity of programming’ to show him the answer – a physical representation of some Very Hard Sums (sums, equations and calculations that are easier now thanks to much faster computers).

A simple and effective way of using water to show a mathematical relationship popped up on QI and the video below demonstrates Pythagoras’ Theorem rather nicely.

In 1939 Lukyanov published an article about his analog hydraulic computer for the (‘Otdeleniye Technicheskikh Nauk’ or ‘Отделение технических наук’ in Russian which means Section for Technical Scientific Works although these days we’d probably say Department of Engineering Sciences) and in 1955 this was translated by the Massachusetts Institute of Technology (MIT) for the US army’s “Arctic Construction and Frost Effects Laboratory”. You can see a copy of his translated ‘Hydraulic Apparatus for Engineering Computations‘ at the Internet Archive.

In a rather pleasing coincidence for this blog post (that you might think was by design rather than just good fortune) this device was actually put to work by the US Army to study the freezing and thawing not of snowmen but of soil (ie, the ground). It’s particularly useful if you’re building and maintaining a military airfield (or even just roads) to know how well the concrete runway will survive changes in weather (and how well your aircraft’s wheels will survive after meeting it).

For a modern take on the ‘hydrodynamic calculating machine’ aka water computer see this video from science communicator Steve Mould in which he creates a computer that can do some simple additions.


2. The puzzle of digital compression

Our snowman’s been sitting around for a while and his ice has probably become a bit compacted, so he might be taking up less space (or he might have melted). Compression is a technique computer scientists use to make big data files smaller.

Big files take a long time to transfer from one place to another. The more data the longer it takes, and the more memory is needed to store the information. Compressing the files saves space. Data on computers is stored as long sequences of characters – ultimately as binary 1s and 0s. The idea with compression is that we use an algorithm to change the way the information is represented so that fewer characters are needed to store exactly the same information.

That involves using special codes. Each common word or phrase is replaced by a shorter sequence of symbols. A long file can be made much shorter if it has lots of similar sequences, just as the message below has been shortened. A second algorithm can then be used to get the original back. We’ve turned the idea into a puzzle that involves pattern matching patterns from the code book. Can you work out what the original message was? (Answer tomorrow).

The code: NG1 AMH5 IBEC2 84F6JKO 7JDLC93 (clue: Spooky apparitions are about to appear on Christmas Eve)

The code book (match the letter or number to the word it codes for).

3. Answer to yesterday’s puzzle

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.