Decoding Rediscovered Rope Memory From The Apollo Guidance Computer

On August 25th, 1966, an Apollo Command Module was launched aboard a Saturn IB rocket in mission AS-202. This mission was intended to immediately precede the ill-fated Apollo 1 mission, the AS-202 was unmanned, serving as a test of flight hardware, fuel cells, and the guidance and navigation control systems. This mission used the first Apollo Guidance Computer ever flown, and this mission was vital to testing the computer that would take men to the moon.

While the software from the later missions exists and is available on Github, the earlier Block I spacecraft, including the unmanned Apollo 4 and Apollo 6 missions, are poorly documented. [Francois Rautenbach] was lucky enough to get his hands on the rope memory modules from the AS-202 mission. Now he’s investigating these modules with oscilloscopes and x-rays to recreate some of the first software that was flown in space.

The procedure to extract the data from these rope memory modules is a bit harder than reading a bit of Flash off a chip. Rope memory is weird, but with a contraption made out of a lot of relays and an oscilloscope, [Francois] was able to capture data from these memory modules.

Of course, [Francois] first needed to figure out the pinout for the gigantic backplane connector on each of these memory modules. To do that, he checked out a Block II AGC, read the schematics very carefully, and reverse engineered a connector that isn’t made anymore. The next step was x-raying the rope memory modules to see how they were assembled. Even though these memory modules contain the only extant copy of the Block I AGC software, even reading one bit off of these modules is an amazing case of technological archeology.

The answer to the obvious question — where did these modules come from — is exactly what you would expect. These memory modules were picked up off a scrap heap forty years ago. The gentleman who found these modules was kind enough to give them to [Francois]. Check out the videos below for [Francois]’ video logs. If you’re into slightly more destructive testing of forgotten Apollo flight hardware, [Fran Blanche] tore down a few modules from the Apollo Launch Vehicle Digital Computer a few years ago.

Thanks to [Vincent], [Danie], and [Kent] for jumping on this one and sending it into the tip line.
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Books You Should Read: Engineer To Win By Carroll Smith

One problem with engineering education today is a lack of experimental teaching. Oh sure you may have a project or two, but it’s not the focus of the program because it’s hard to standardize a test around. Typically sections of the field are taught in a highly focused theoretical course by a professor or graduate student with a specialization in that section. Because classes treat individual subject areas, it’s entirely possible to get a really good understanding of two pieces of the same puzzle, but never realize that they fit together to make a picture. It’s only when a freshly minted engineer gets out into the real world that they start to make the connections between seemingly disparate fields of knowledge.

This is why Carroll Smith’s book “Engineer to Win” is so good. He spent a lifetime as a practicing engineer in a field where a small failure could mean the death of a friend. So when he set out to write a book, he wrote a book that related everything needed to properly conceptualize and solve the mechanical engineering problems in his field.

One warning though; the book is not for the faint of heart. If you want to learn something difficult well, then this is book for you. Carroll skips the comforting analogies and gives the information exactly. It can get a little dense, but he makes the assumption that the reader is there to learn and, most importantly, understand. This takes work.

2016-08-01_02h06_34For example, you can’t really understand why a rolled bolt is stronger than a bolt cut on a screw machine until you understand how metal works on a crystalline level. The same goes for metal fatigue, brittle fractures, ductile failures, and all the maladies that metal can suffer. The difference between an engineer and a technician is this deep understanding. Otherwise the equations learned are just parts in a toolbox and not paint on an artist’s palette.

This is why the first half of the book is dominated by all things metallurgical. The book starts with the simple abstractions of the crystalline structures of metal. Unlike my materials class in university, it maintains a practical bend to the presentation of the information throughout the whole process. For example, it moves on to what all this practically means for metals undergoing stresses and failures before it launches into a (short) digression on how metals are made and their history.

However, if racecar plumbing is your thing his treastise, "Carroll Smith's Nuts, Bolts, Fasteners and Plumbing Handbook" is also fantastic.
However, if racecar plumbing and fasteners are kinda your thing, “Carroll Smith’s Nuts, Bolts, Fasteners and Plumbing Handbook” is also a fantastic read.

This first half of the book touches on non-ferrous metals and their proper use as well. After that comes some of the best explanations of metal fatigue, fasteners, and metal bonding I’ve ever read. When the failure of a joint causes a mechanism to fail in a toaster that’s one thing, but when it fails in a racecar people get hurt. Carroll is very exacting in what constitutes a forgivable oversight in engineering, and what does not.

Once the book has finished conveying a working understanding of metals and fasteners it seems to fracture into a pot-luck of different racecar-related topics. During my first reading of the book I resisted this strange turn of events. For example, I didn’t really want to read about racecar plumbing in the eighties, or what kind of springs and aerofoils Carroll likes. However, when I reread those sections in a more focused manner, I realized that many of them were teaching the practical application of the knowledge learned in the previous chapters. How does the metal make a good spring? Why is one kind of plumbing better than another?

Importantly, the anecdotes at the end of the book impart an understanding of the importance of professionalism in engineering. What is the true responsibility of an engineer? He teaches not to take the trust others place in your skills for granted. He teaches to trust in the skills of others. The book teaches humility as an engineer. He shows the kind of person one can become after a lifetime of earnest study in their craft.

Thanks to reader, [Dielectric], for recommending the book to me. Also, from the bit of research I’ve done, the older motorworks edition is generally considered to have better quality reproductions of the diagrams than the newer printings of the book.

Mini Plasma Cutter

What do you get when you combine an arc cigarette lighter and some scrap glass and metal? [NightHawkInLight] created a simple plasma cutter project along with some hot glue and a few simple tools.

If you aren’t a smoker, an arc lighter uses a high voltage spark to light the cigarette. He essentially cannibalizes it for use as a power supply. Any similar high-voltage power supply should work just as well. He also uses the same cigarette lighter power supply for an arc pen, that we covered earlier.

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From Project To Kit: After The Sale

However you sell your kits online, you’ll have to find a means of shipping them to the customer. For an online operation this unseen part of the offering is more important than any other when it comes to customer satisfaction, yet so many large players get it so wrong.

This is the final article in a series looking on the process of creating and selling a commercial kit from a personal electronic project (read all the posts in this series). We’ve looked at the market, assembling the kit and its instructions, and how to set up an online sales channel. In this part we’ll look at what happens when you’ve made the sale, how to get it safely to the customer and how to keep the customer happy after the sale by offering support for your products. We’ll also give a nod to marketing your site, ensuring a fresh supply of customers.

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“Starry Night” Dress Shines On The Experience Of Multiple Builds

[Dave Hrynkiw] wrote up some practical and useful detail around embedding electronics into clothing. It centers around his daughter’s “Starry Night” high school graduation dress, which is the culmination of a lot of experimentation in finding the best way to do things. His daughter accented the dress with LEDs to produce a twinkling starfield effect, and a laser-cut RGB pendant to match.

While [Dave] is the president of Solarbotics and pitches some products in the process of writing it all up, the post is full of genuinely useful tips that were all learned though practical use and experimentation. Imagine how awesome it must be growing up a child of a “local technology-hacking company” founder — akin to growing up as Willy Wonka’s progeny.

What advice does [Dave] have for making electronics an awesome part of garments? For example, the fact that regular hookup wire isn’t very well suited to embedding into clothing due to the need for high flexibility. There is also the concept of sequestering electronics into a separate Technology Layer — a must for anything that will be used more than once. The idea is to “build your technology so it can be isolated from the fashion aspect as much as possible. It makes building and maintenance of both the fashion and technology aspects much simpler.”

Slapping some LEDs and a battery pack into clothing might do the trick if all you care about is some bling, but if you want something that actually highlights and complements clothing while also being able to stand up to repeated use, this is a great read. A simple lighting effect that complements a design isn’t difficult, and there’s no need to reinvent the wheel or make the same mistakes others have encountered. Video is embedded below.

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Racing Roomba Packs The Power To Pop Wheelies

This is just good, clean fun. Well, maybe not clean since this souped-up racing Roomba appears to move too fast to actually clean anything anymore. But did they ever really clean very well in the first place?

W6yAwJ[Roland Saekow] doesn’t offer much in the way of build details, but the starting point was a 10-year old Roomba Discovery. The stock motors were replaced with 600RPM planetary drive motors and a whopping 12A motor controller. The whole thing is powered off the standard Roomba 14.4V battery pack, but we suspect not for long. Those motors have got to suck down the juice pretty fast to be able to pop wheelies and pull hole shots like it does in the video below.

No word either on how it’s being controlled; our guess is RC, since it looks like the collision sensor grazes a chair leg slightly around the 0:33 mark, but doesn’t seem to change direction. It’d be cool if it could operate autonomously, though. We wonder how it would deal with the Virtual Walls at those speeds.

File this one under “Just for Fun” and maybe think about the possibilities for your defunct Roomba. If speed-vacuuming isn’t your thing, there are plenty of other Roomba hacks around here.

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Hackaday Prize Entry: Magic Bit-Of-Wire Motion Detector Library For Arduino

We’re still not sure exactly how [connornishijima]’s motion detector works, though many readers offered plausible explanations in the comments the last time we covered it. It works well enough, though, and he’s gone and doubled down on the Arduino way and bundled it up nicely into a library.

In the previous article we covered [connor] demonstrating the motion detector. Something about the way the ADC circuit for the Arduino is wired up makes it work. The least likely theory so far involves life force, or more specifically, the Force… from Star Wars. The most likely theories are arguing between capacitance and electrostatic charge.

Either way, it was reliable enough a phenomenon that he put the promised time in and wrote a library. There’s even documentation on the GitHub. To initialize the library simply tell it which analog pin is hooked up, what the local AC frequency is (so its noise can be filtered out), and a final value that tells the Arduino how long to average values before reporting an event.

It seems to work well and might be fun to play with or wow the younger hackers in your life with your wizarding magics.