instructional

3 Articles

Retrotechtacular: Learning The Slide Rule The New Old Fashioned Way

December 2, 2025 by No comments

Learning something on YouTube seems kind of modern. But if you are watching a 1957 instructional film about slide rules, it also seems old-fashioned. But Encyclopædia Britannica has a complete 30-minute training film, which, what it lacks in glitz, it makes up for in mathematical rigor.

We appreciated that it started out talking about numbers and significant figures instead of jumping right into the slide rule. One thing about the slide rule is that you have to sort of understand roughly what the answer is. So, on a rule, 2×3, 20×30, 20×3, and 0.2×300 are all the same operation.

You don’t actually get to the slide rule part for about seven minutes, but it is a good idea to watch the introductory part. The lecturer, [Dr. Havery E. White] shows a fifty-cent plastic rule and some larger ones, including a classroom demonstration model. We were a bit surprised that the prestigious Britannica wouldn’t have a bit better production values, but it is clear. Perhaps we are just spoiled by modern productions.

We love our slide rules. Maybe we are ready for the collapse of civilization and the need for advanced math with no computers. If you prefer reading something more modern, try this post. Our favorites, though, are the cylindrical ones that work the same, but have more digits.

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MeArm 3.0: The Pocket-Sized Robot Arm

June 26, 2023 by 14 Comments

We all might dream of having an industrial robot arm at our disposal, complete with working controller that doesn’t need constant maintenance and replacement parts, and which is able to help us with other projects with only a minimum of coding or instruction. That’s a pipe dream for most of us, as without a large space, sufficient funding, or unlimited amounts of troubleshooting time we’ll almost always have to look for something smaller and simpler. Perhaps something even as small as this pocket-sized robotic arm.

This isn’t actually the first time we’ve seen the MeArm; the small robot has been around since 2014 and has undergone a number of revisions and upgrades. Even this revision has been out for a little while now but this latest in the series is now available with a number of improvements over the older models. The assembly time required has been reduced from two hours to about 30 minutes and the hardware has even been fully open-sourced as well which allows virtually anyone with the prerequisite tools to build this tiny robot for whatever they happen to need it for, due to its very permissive licensing.

The linked Instructable goes into every detail needed for building the robot as well as documenting all of the parts needed, although you will need access to some specialty tools to make a lot of them. We also featured a Friday Hack Chat about these robots back in 2018 that has some interesting details about these robots in it, and although this is a relatively small robot in the grand scheme of things it’s always possible to upgrade to something larger in the future.

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All You’ve Ever Wanted To Know About Compilers

January 5, 2020 by 21 Comments

They say that in order to understand recursion, you must first understand recursion. Once you master that concept, you might decide that it’s time to write your own compiler that can compile itself as a fun side project. According to [Warren] aka [DoctorWkt], who documented every step of writing this C compiler from scratch, a true compiler will be able to do that.

Some of the goals for the project included self-compiling, focusing on a real hardware platform, practicality, and simplicity. [Warren] outlines a lot of the theory of compilers as well, including all the lexical, grammar, and semantic analysis and then the final translation into assembly language, but really focuses on making this compiler one for practical use rather than just a theoretical implementation. He focuses on Intel x86-64 and 32-bit ARM platforms too, which are widely available.

This project is a long read and very thoroughly documented at around 100,000 words, so if you’ve ever been interested in compilers this is a great place to start. There are a lot of other great compiler tools floating around too, like the Compiler Explorer which shows you generated code as you write in a higher level language.

[via Hackaday.io]