Back (page) to the drawing board

by Jo Brodie, Queen Mary University of London

Dart in bullseye of dartboard
Image by StockSnap from Pixabay

Here are some more cunning contraptions, with and without a purpose…


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Tempest Prognosticator: look out, leeches!

by Jo Brodie, Queen Mary University of London

raindrops on a window
Image by Kranich17 from Pixabay

When we leave our homes we might check a weather app to give us predictions from number-crunching computers, to see if we’ll need an umbrella, but in the mid-1800s the appropriately named George Merryweather thought he’d make use of the alleged weather predicting properties of leeches to create a ‘leech barometer’ to measure the weather. His notion relied on the belief that leeches, kept inside small glass bottles, would try and escape when a storm was due (because they might be more sensitive to subtle changes in electrical conditions in the air that we humans would miss). The escaping leeches would trigger a small hammer placed above the bottles which would strike a bell and alert everyone in earshot that a storm might be imminent and also that your living room was about to be overrun with leeches. Not surprisingly it wasn’t very popular, though Merryweather claimed to have great success with it.


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Quipu: tie a knot in it

by Jo Brodie, Queen Mary University of London

A string with lots of multicoloured strings attached to it, each with knots tied down them
Quipu in the Museo Machu Picchu, Casa Concha, Cusco
Image by Pi3.124 from Wikimedia CC-BY-SA-4.0

Quipu (the Quechua word for ‘knot’) are knotted, and sometimes differently coloured, strings, made from the hair fibres of llamas or alpacas. They were used by people, such as the Incas, living hundreds of years ago in Andean South America. They used the quipu to keep numeric trade or military records. A ‘database’ was formed of several of the strings tied together at one end. Each string stored numbers as different kinds of knots at different positions along the strings, with positions for ones, tens, hundreds, etc. It worked a bit like an abacus, but with much less danger of losing your work if you turn it upside down. The number ‘1’ was represented as a figure-of-eight knot in the ones position and ‘40’ could be indicated by four simple knots in the tens position. Not many quipu survive and even fewer have been decoded, but anthropologists have begun to find evidence that they might contain not just numbers but a written (well, a tactile) form too.


Make your own Quipu

Make your own Quipu decoration or necklace that represents something by tying knots in coloured string or ribbons.

  1. It could keep track of important numbers for you, such as how much pocket money you have at the end of each week, making a new string (or ribbon) for each week, or
  2. Store some sequence of numbers in a sequence of quipu like the 3 times table or the square numbers or the Fibonacci numbers…, or
  3. Invent a code such as A=1, B=2, … and store a message on your Quipu by spelling it out in numbers and so knots.
A Quipu showing 26 or if using a simple number-letter code, Z

To make your Quipu more colourful tie different coloured strings together end to end to make a single Quipu. One colour string then represents ones and the next tied to it represents tens for a single number and so letter (and so on). Use different colours for your next Quipu.


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Bullseye! The intelligent dart board

by Jo Brodie, Queen Mary University of London

A dart in the bulls eye of a dartboard
Image by StockSnap from Pixabay

Mark Rober, an engineer and YouTuber who worked for NASA, has created a dartboard that jumps in front of your dart to land you the best score. Throw a dart at his board and infra-red motion capture cameras track its path, and, software (and some maths) predicts where it will land. Motors then move the dartboard into a better position to up the score in real time!


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

The Ultimate (do nothing) machine

by Jo Brodie, Queen Mary University of London

A black box with an on-off switch at ON. The top flips open and a robotivc finger pokes out to push the switch back to OFF.
This ultimate machine is a commercially produced version of Minsky’s idea. Image by Drpixie from Wikimedia CC-BY-SA-4.0

In 1952 computer scientist and playful inventor, Marvin Minsky, designed a machine which did one thing, and one thing only. It switched itself off. It was just a box with a motor, switch and something to flip (toggle) the switch off again after someone turned it on. Science fiction writer Arthur C. Clarke thought there was something ‘unspeakably sinister’ about a machine that exists just to switch itself off and hobbyist makers continue to create their own variations today.


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Simone Giertz: A pat on the shoulder

The Proud Parent Machine

by Jo Brodie, Queen Mary University of London

A pat on the shoulder In lockdown, during the Covid-19 pandemic, inventor and roboticist Simone Giertz created a coin-operated ‘proud parent machine’ which, for 25 US cents, would pat her on the shoulder and give a few words of encouragement. Putting in a coin sent a signal to a microcontroller that turned a motor on which lowered a 3D-printed arm (to pat her shoulder), then played a pre-recorded audio file telling her how proud of her the automaton was. Making the machine involved skills in woodworking, computer-aided design, mechanics and electronics. She also gave a TED Talk called “Why you should make useless things”.


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Sophie Wilson: Where would feeding cows take you?

Chip design that changed the world

by Paul Curzon, Queen Mary University of London

(Updated from the archive)

cows grazing
Image by Christian B. from Pixabay 

Some people’s innovations are so amazing it is hard to know where to start. Sophie Wilson is like that. She helped kick start the original 80’s BBC micro computer craze, then went on to help design the chips in virtually every smartphone ever made. Her more recent innovations are the backbone that is keeping broadband infrastructure going. The amount of money her innovations have made easily runs into tens of billions of dollars, and the companies she helped succeed make hundreds of billions of dollars. It all started with her feeding cows!

While still a student Sophie spent a summer designing a system that could automatically feed cows. It was powered by a microcomputer called the MOS 6502: one of the first really cheap chips. As a result Sophie gained experience in both programming using the 6502’s set of instructions but also embedded computers: the idea that computers can disappear into other everyday objects. After university she quickly got a job as a lead designer at Acorn Computers and extended their version of the BASIC language, adding, for example, a way to name procedures so that it was easier to write large programs by breaking them up into smaller, manageable parts.

Acorn needed a new version of their microcomputer, based on the 6502 processor, to bid for a contract with the BBC for a project to inspire people about the fun of coding. Her boss challenged her to design it and get it working, all in only a week. He also told her someone else in the team had already said they could do it. Taking up the challenge she built the hardware in a few days, soldering while watching the Royal Wedding of Charles and Diana on TV. With a day to go there were still bugs in the software, so she worked through the night debugging. She succeeded and within the week of her taking up the challenge it worked! As a result Acorn won a contract from the BBC, the BBC micro was born and a whole generation were subsequently inspired to code. Many computer scientists, still remember the BBC micro fondly 30 years later.

That would be an amazing lifetime achievement for anyone. Sophie went on to even greater things. Acorn morphed into the company ARM on the back of more of her innovations. Ultimately this was about returning to the idea of embedded computers. The Acorn team realised that embedded computers were the future. As ARM they have done more than anyone to make embedded computing a ubiquitous reality. They set about designing a new chip based on the idea of Reduced Instruction Set Computing (RISC). The trend up to that point was to add ever more complex instructions to the set of programming instructions that computer architectures supported. The result was bloated systems that were hungry for power. The idea behind RISC chips was to do the opposite and design a chip with a small but powerful instruction set. Sophie’s colleague Steve Furber set to work designing the chip’s architecture – essentially the hardware. Sophie herself designed the instructions it had to support – its lowest level programming language. The problem was to come up with the right set of instructions so that each could be executed really, really quickly – getting as much work done in as few clock cycles as possible. Those instructions also had to be versatile enough so that when sequenced together they could do more complicated things quickly too. Other teams from big companies had been struggling to do this well despite all their clout, money and powerful computer mainframes to work on the problem. Sophie did it in her head. She wrote a simulator for it in her BBC BASIC running on the BBC Micro. The resulting architecture and its descendants took over the world, with ARM’s RISC chips running 95% of all smartphones. If you have a smartphone you are probably using an ARM chip. They are also used in game controllers and tablets, drones, televisions, smart cars and homes, smartwatches and fitness trackers. All these applications, and embedded computers generally, need chips that combine speed with low energy needs. That is what RISC delivered allowing the revolution to start.

If you want to thank anyone for your personal mobile devices, not to mention the way our cars, homes, streets and work are now full of helpful gadgets, start by thanking Sophie…and she’s not finished yet!


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This blog is funded by UKRI, through grant EP/W033615/1.

The Hive at Kew

Art meets bees, science and electronics

by Paul Curzon, Queen Mary University of London

(from the archive)

a boy lying in the middle of the Hive at Kew Gardens.

Combine an understanding of science, with electronics skills and the creativity of an artist and you can get inspiring, memorable and fascinating experiences. That is what the Hive, an art instillation at Kew Gardens in London, does. It is a massive sculpture linked to a subtle sound and light experience, surrounded by a wildflower meadow, but based on the work of scientists studying bees.

The Hive is a giant aluminium structure that represents a bee hive. Once inside you see it is covered with LED lights that flicker on and off apparently randomly. They aren’t random though, they are controlled by a real bee hive elsewhere in the gardens. Each pulse of a light represents bees communicating in that real hive where the artist Wolfgang Buttress placed accelerometers. These are simple sensors like those in phones or a BBC micro:bit that sense movement. The sensitive ones in the bee hive pick up vibrations caused by bees communicating with each other The signals generated are used to control lights in the sculpture.

A new way to communicate

This is where the science comes in. The work was inspired by Martin Bencsik’s team at Nottingham Trent University who in 2011 discovered a new kind of communication between bees using vibrations. Before bees are about to swarm, where a large part of the colony split off to create a new hive, they make a specific kind of vibration, as they prepare to leave. The scientists discovered this using the set up copied by Wolfgang Buttress, using accelerometers in bee hives to help them understand bee behaviour. Monitoring hives like this could help scientists understand the current decline of bees, not least because large numbers of bees die when they swarm to search for a new nest.

Hear the vibrations through your teeth

Good vibrations

The Kew Hive has one last experience to surprise you. You can hear vibrations too. In the base of the Hive you can listen to the soundtrack through your teeth. Cover your ears and place a small coffee stirrer style stick between your teeth, and put the other end of the stick in to a slot. Suddenly you can hear the sounds of the bees and music. Vibrations are passing down the stick, through your teeth and bones of your jawbone to be picked up in a different way by your ears.

A clever use of simple electronics has taught scientists something new and created an amazing work of art.


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EPSRC supports this blog through research grant EP/W033615/1, and through EP/K040251/2 held by Professor Ursula Martin. 

The beach, the missionary and my origin myth

by Paul Curzon, Queen Mary University of London

An open book on the sand of a beach with blue sea and sky behind
Image by StockSnap from Pixabay

Superheroes always have an origin myth that describes how they emerged as a hero. Spider-man has his spider bite and death of his uncle; Batman, his fall into a cave full of bats and the murder of his parents; Captain Marvel was exposed to an alien energy source… Why not work out your own origin myth? Everyone should have one. Mine involves a beach, a book of programs, and before that a missionary. It is the backstory of how I became a computer scientist.

The beach

My origin myth usually begins with a beach and a book containing some programs, some articles about computers and some computing cartoons. The articles were vaguely interesting, some of the cartoons were funny, but the program listings were fascinating: a whole new language that made computers tick.

At that point computers were way too expensive for me to dream of owning one (and in any case back then there were no mobile computers so unlike now, you certainly couldn’t take one to the beach). All I had was my imagination, but that was enough to get me started.

With nothing else to do on the beach (it was too hot to move), I spent my time lying in the sun reading programs and trying to work out what they did and how they did it. With no computer, all I could do was pretend to be the computer myself, stepping through the listings line by line with paper and pen, writing out the changing numbers stored (their variables) and what they printed. I then moved on to writing some simple game programs myself, like a cricket game. I wrote them in my notebook and again pretended I was the computer to make them work. By the end of the holiday I could program.

Ada Lovelace

I didn’t discover this till decades later but Ada Lovelace, the famous Victorian computer pioneer working with Charles Babbage was in a similar position (well sort of … she was a rich countess, I wasn’t). She also had no computer as Babbage hadn’t managed to fully build his. She had no programming language either to write programs in, or for that matter any actual programs to read. However, she had some algorithms written by Babbage that he intended his machine’s programs would be based on. Just like me, she stepped through the algorithms on paper, working out what they would do (should Babbage ever build his computer), step by step. As a result she learnt about the machine and as it happens also found a mistake in one algorithm. The table she drew of the computer working is often taken as proof she was the ‘first programmer’, though as Ursula Martin, who studied her papers, has pointed out, it is not a program. It is an execution trace or ‘dry run table’. She was actually the first ‘execution tracer’ or ‘dry-runner’.

The importance of dry running code

Dry running programs like this on paper is not just a useful thing for people with no computer, it is also a critical thing for anyone learning to program to do – a way of actively reading programs. You didn’t learn to write English (or any other language) by just writing, you read lots too and the same goes for programming. It turns out that the way I taught myself to program is a really, really powerful way to do so.

Just as importantly dry running programs on paper in this way is also important as a way of checking that programs work as Lovelace found. The modern version is the code walkthrough – a powerful technique that complements testing programs as a way of discovering problems.

The missionary

While that is the point in time when I learnt to program, there was someone earlier who originally inspired me about computation: a missionary. Sadly I don’t know his name, but he came to our school to talk about his life as a missionary in Papua New Guinea. He told us that one of the problems of travelling there was that communities were isolated from each other and each village spoke its own language. That meant that, as he travelled around, he had a big problem speaking to anyone. Every time he moved on he had a new language to learn or an old one of many to remember. It wasn’t the idea of converting people, or travelling to exotic places that means I remember him more than 40 years later. It was what he showed us next: how he solved the problem. He pulled out a massive pile of cards with holes punched round the edges, labelled with letters. Each had a word written on it in English as well as words in other languages from different places. He spelled out a word a letter at a time (pig was the example he used) by putting a knitting needle through a hole in all the cards next to the letter. Those that fell out were used for the next letter and so on. After three rounds just the card for pig fell out, as if by magic. It wasn’t magic though, it was computation. On the pig card he had cut notches in the holes for p, i and g. As that was the only word with those letters, it was the only card that could fall out for all three letters and then he could read off the translation for the village he was in..

Bitten by a bug

What the missionary was showing us was an edge-notched card system (see the ‘Wood computer’, page 16). I was fascinated and have been ever since about computation, especially when it’s done physically. It was that general fascination for algorithms that led me to want to learn to program.

In my origin story, I was bitten by a bug: the missionary converted me… to computer science.


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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

Hoverflies: comin’ to get ya

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

(from the archive)

A hoverfly on a blade of grass

By understanding the way hoverflies mate, computer scientists found a way to sneak up on humans, giving a way to make games harder.

When hoverflies get the hots for each other they make some interesting moves. Biologists had noticed that as one hoverfly moves towards a second to try and mate, the approaching fly doesn’t go in a straight line. It makes a strange curved flight. Peter and his student Andrew Anderson thought this was an interesting observation and started to look at why it might be. They came up with a cunning idea. The hoverfly was trying to sneak up on its prospective mate unseen.

The route the approaching fly takes matches the movements of the prospective mate in such a way that, to the mate, the fly in the distance looks like it’s far away and ‘probably’ stationary.

Tracking the motion of a hoverfly and its sightlines

How does it do this? Imagine you are walking across a field with a single tree in it, and a friend is trying to sneak up on you. Your friend starts at the tree and moves in such a way that they are always in direct line of sight between your current position and the tree. As they move towards you they are always silhouetted against the tree. Their motion towards you is mimicking the stationary tree’s apparent motion as you walk past it… and that’s just what the hoverfly does when approaching a mate. It’s a stealth technique called ‘active motion camouflage’.

By building a computer model of the mating flies, the team were able to show that this complex behaviour can actually be done with only a small amount of ‘brain power’. They went on to show that humans are also fooled by active motion camouflage. They did this by creating a computer game where you had to dodge missiles. Some of those missiles used active motion camouflage. The missiles using the fly trick were the most difficult to spot.

It just goes to show: there is such a thing as a useful computer bug.


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EPSRC supports this blog through research grant EP/W033615/1, and through EP/K040251/2 held by Professor Ursula Martin.