Category Archives: General

How to preview fixed width (mono spaced) fonts in an editable Emacs buffer?

When using Emacs, I don’t spend time thinking about fonts most of the time. Like the majority, I pick my favorite fixed width, mono space font and get on with it. Every now and then I can hear about some cool new font for reading lots of software source code and technical writing, and I might give it a try, but that’s the end of it.

But sometimes, you just want to have an overview and see everything summed up in a single place, preferably an Emacs buffer so you can also play with it and hack it. Of course, your GNU/Linux, macOS, or MS Windows will happily show you all the available fonts, and let you filter out fixed width ones suitable for programming. Emacs itself can also do something very similar. But as I said, why not have something according to your taste?

With a bit of Emacs Lisp, it seems not that difficult, at least on GNU/Linux:

The result of running compare-monospace-font-families can be seen in the following screenshot: Read the rest of this entry »

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Posted by on May 9, 2019 in Emacs, General


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A visit to the largest computer museum in the world: The Heinz Nixdorf MuseumsForum

It all started more than seven years ago, when I read a short article in January, 2010 issue of Communications of the ACM, titled “Great Computing Museums of the World (Part One)“.

“The Heinz Nixdorf MuseumsForum (HNF; in Paderborn, Germany, is the world’s largest computer museum. The museum, which is also an established conference center, showcases the history of information technology—beginning with cuneiform writing and going right through to the latest developments in robotics, artificial intelligence, and ubiquitous computing.

The multimedia journey through time takes visitors through 5,000 years of history, starting with the origins of numbers and writing in Mesopotamia in 3000 B.C. and covering the entire cultural history of writing, calculating, and communications. Alongside typewriters and calculating machines, the exhibition shows punched card systems, a fully functioning automatic telephone exchange system from the 1950s, components from the earliest computer (which filled a whole room), over 700 pocket calculators, and the first PCs. Work environments from different centuries are also staged in the exhibition.

The exhibition highlights include fully functioning replicas of the Leibniz calculating machine and the Hollerith tabulating machine, a Thomas Arithmometer dating from 1850, a Jacquard loom operated with punched tape, components of the ENIAC from 1945, the on-board computer from the Gemini space capsule, the Apple 1, a LEGO Turing machine, and Europe’s largest collection of cipher machines. One of the current attractions at HNF is the world’s most famous automaton: Wolfgang von Kempelen’s chess playing machine, the Chess Turk, which dates from the 18th century.”

I was more than impressed, and wanted to visit Paderborn to see the world’s largest computer museum. I knew it was just a few hours away by car from Antwerp, but I’ve always postponed going there for various reasons. I didn’t want there to go alone, and I knew I needed someone like-minded enough to accompany me on this “nerdy” journey. Finally, last week, I and a physicist / data scientist friend of mine decided to go there, notwithstanding the weather conditions, and very snowy German highways.

I think this is the only museum where digital relics from my childhood and youth (1980s and 1990s) are considered as museum-worthy as replicas of 5000 year old Sumerian tablets! 🙂 It was pure joy and fascination to visit the halls of the museum, and be guided by very thematic and knowledgeable, gentle robots. One of them, Victoria, was a sight to be seen! The other one was also great, and you can watch “him” in action:

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Posted by on December 17, 2017 in General, Science



Do Great Minds Necessarily Need Fancy Technology to Collaborate?

We’re living in the age of touch enabled wireless devices that are connected to Internet almost always. We can have instant one-to-one video communication very easily and cheaply. It is possible to organize video teleconferences with many participants instantly (well, the last part might be a little exaggerated). Scientists and programmers separated from each other by thousands of kilometers and many time zones can work and collaborate on projects daily. It is almost natural to think that, without such technologies, we would be living in dark ages, and our greatest thinkers would suffer from isolation miserably. But is it really the case?

The following pages are from the chapter titled “Was Cantor Surprised?”, from a popular mathematics book, The Best Writing on Mathematics 2012:


Let’s focus on those particular sentences: Read the rest of this entry »

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Posted by on October 18, 2015 in General


De Olifant in het Bad: Een interactieve iPad boek voor kinderen

De olifant in het bad is een interactief boek voor kinderen tussen 1 en 10 jaar oud. Het verhaal gaat over een meisje, Zara en een olifant. Zara hoort een gedruppel in het huis. Vanwaar zou dit toch komen? Is er een olifant in het bad misschien?

Laat je kind ermee spelen! Belletjes ploffen, de bal gooien, verschillende gereedschappen gebruiken om het bad te herstellen, de olifant meehelpen… Ontdek het verborgen object op elke pagina. Vind je het haar van Zara niet leuk? Verander het dan maar… Je kan zelfs de zon verplaatsen.

De Olifant in het Bad: Een interactieve iPad boek voor kinderen

De Olifant in het Bad: Een interactieve iPad boek voor kinderen

Het originele versie van het boek is in het Engels. Het is vertaald en verteld door Tanya Gezgen zodat Nederlandstalige kinderen er ook veel plezier aan kunnen beleven.
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Posted by on May 10, 2012 in General


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Do you want to join NASA International Space Apps Challenge?

From their exciting web page:

“The International Space Apps Challenge team has collected these challenges from throughout NASA and our international partners to serve as an inspiration for projects that could be created. Our goal is to provide a platform for people interested in space exploration to get together to work on amazing projects together, and we encourage you to come up with your own projects and submit them for inclusion on this list on the Challenge Submission page.”

NASA International Space Apps Challenge

NASA International Space Apps Challenge

I’m happy to see that Istanbul was one of the selected locations.

Some of the challenges are:

Fragile Oasis: Map-a-Difference
Visualize the “All-too-Common Astronomy/Solar System Misconceptions”
Aurora Layer for Google Earth
Dark Skies App
Handheld Hardware for Citizen Science
NASA Planetary Data System Interface
Create Semantic Data Descriptor File
HTML5 App to access NASA Earth Observations website
Suborbital Payload for Citizen Science (Pressurized)
MathTrax Challenges
A New Command and Control Protocol for CubeSats


Posted by on April 9, 2012 in General, Programlama, Science


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Programming for Kids – Robocup Junior 2012 @ Technopolis

Thanks to the members of Devoxx4Kids, I have recently learned about a very interesting event: Robocup Junior 2012. This year’s event is organized at Technopolis, so I decided to go there with my wife and 8 month old son today (well, it is never too early to start, right?).

I was really surprised by the number of children at the event. The robotics tournament took place at a hall and most of the kids were either rushing to place their various robots on different challenge tracks, or very concentrated and busy on their laptops, trying to do the last minute bug fixes.

From robots running for rescue missions, to the ones that solved Rubik’s cube, the event was full of excitement, hacking and creativity. I also had the chance to drop by the Dwengo stand to see their robotics kit, powered by the famous Dwengo board. All that is left to do now is to find out how I can introduce all of this robotics to my students who learn programming in Scratch.

Below you can watch a slideshow of photos from the event.

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Posted by on March 11, 2012 in General, Programlama


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Why are these two maps so similar? (Curious about Belgium)

I have recently discovered a very interesting map on the web site. It shows the number of .be Internet domains per inhabitants as of 2011 in Belgium.

Domains per 1000 inhabitants in 2011

Domains per 1000 inhabitants in 2011

If you compare this map with the map of the Flemish region:

Flemish region in Belgium

Flemish region in Belgium

The similarity is obvious. What may be the reasons of this similarity? Any ideas?


Posted by on March 3, 2012 in General


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