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.
Continue reading “Decoding Rediscovered Rope Memory From the Apollo Guidance Computer”

Hackaday Links: August 14, 2016

Hey London peeps! Hackaday and Tindie are doing a London meetup! It’s this Wednesday, the 17th.

What do you do if you need Gigabytes of storages in the 80s? You get tape drives. What do you do if you need Terabytes of storage in the year 2000? You get tape. The IBM Totalstorage 3584 is an automated tape storage unit made sometime around the year 2000. It held Terabytes of data, and [Stephen] picked up two of them from a local university. Here’s the teardown. Unfortunately, there’s no footage from a GoPro stuck inside the machine when it’s changing tapes, but the teardown was respectable, netting two drives, the power supplies, and huge motors, fans, relays, and breakers.

A few years ago Motorola released the Lapdock, a CPU-less laptop with inputs for HDMI and USB. This was, and still is, a great idea – we’re all carrying powerful computers in our pocket, and carrying around a smartphone and a laptop is effort duplication. As you would expect, the best use for the Lapdock was with a Raspberry Pi, and prices of Lapdocks have gone through the roof in the last few years. The Superbook is the latest evolution of this Lapdock idea. It’s a small, thin, CPU-less laptop that connects to a phone using a special app and a USB cable. It also works with the Raspberry Pi. Very interesting, even if they didn’t swap the CTRL and Caps Lock keys as God intended.

Did you know we have a store? Yes! It’s true! Right now we need to get rid of some stuff, so we’re having a clearance sale. We got FPGA Arduino shields! Buy a cordwood puzzle! SUPERLIMINAL ADVERTISING.

The computers aboard Federation vessels in the 24th century were based on isolinear chips. Each chip plugged into a backplane, apparently giving certain sections of the ship different functions. Think of it as a reconfigurable PDP Straight-8. This is canon, from TNG, and doesn’t make any sense. [Bohrdasaplank] over on Thingiverse has a few different models of isolinear chips. After close examination of these chips, we can only come to one conclusion.

How do you get a pilot bearing out of a motor? The normal way is using grease (or caulk, or some other gooey substance) as a hydraulic ram, but a slice of bread works much better. This is a weird one, but it works perfectly, with hardly any cleanup whatsoever.

542-page PDF warning here. Here’s the operations manual for the Apollo 15, including operation of the AGC, how to fly the LM, the planned traverses and EVAs, and a nice glossary of handy equations. If anyone’s looking for a LaTeX, InDesign, or bookbinding project that would make the perfect bathroom reader, this is it.

Here’s something I’ve been having trouble with. This is an mATX computer case with a screen on the side and a cover for the screen that includes a keyboard and trackpad. Yes, it’s a modern version of the luggable, ‘portable’, plasma-screen monsters of the 80s. I don’t know where I can buy just the case, so I’m turning to the Hackaday community. There’s an entire line of modern luggable computers made by some factory in Taiwan, but as far as I can tell, they only sell to resellers who put their own mobo and CPU in the machine. I just want the case. Where can I buy something like this? If you’re asking why anyone would want something like this, you can put two 1080s in SLI and still have a reasonably portable computer. That’s a VR machine, right there.

Riding Shotgun In The Apollo 12 Lunar Lander

Last week we had a walk through of the Lunar Module’s source code with Don Eyles, who wrote the landing programs. Now you can take a rather thrilling ride to see Don’s code in action.

Below is an annotated video of the Apollo 12 landing, in real-time. It’s worth setting aside a quarter-hour to check it out. In an age where everyone is carrying around an HD (or way better) camera in their pocket, following along with radio broadcasts, still images, and small slivers of video might not sound that awesome. But it is!

p63-apollo-12-codeThe video takes us from Powered Descent Initiation through touchdown on the Moon with Pete Conrad and Alan Bean. As the audio plays out the video has annotations which explain what is going on and that translate the jargon used by the team. With the recently celebrated push to publish the source code you can even follow along as the video displays which program is running at that time. Just search for the program code and you’ll find it, like this screenshot of the P63 routine. The code comments are more than enough to get the gist of it all.

If you enjoy this, the description of the YouTube video below includes links to similar videos for Apollo 11, 14, 15, 16, and 17.

[Thanks to Paul Becker for sending along this video]

Don Eyles Walks Us Through the Lunar Module Source Code

A couple weeks ago I was at a party where out of the corner of my eye I noticed what looked like a giant phone book sitting open on a table. It was printed with perforated green and white paper bound in a binder who’s cover looked a little worse for the wear. I had closer look with my friend James Kinsey. What we read was astonishing; Program 63, 64, 65, lunar descent and landing. Error codes 1201, 1202. Comments printed in the code, code segments hastily circled with pen. Was this what we thought we were looking at? And who brings this to a party?

Continue reading “Don Eyles Walks Us Through the Lunar Module Source Code”

Cover Your Glass: A Lesson in Design Trades

Penn and Teller once had a show about “What is the best?” Engineers know that’s not a complete question. Think about a car. What makes the “best” car? It depends on why you want a car. For a race car driver, it might be that speed is the most important factor. A mom might value safety. Someone who commutes four hours a day might like a car that’s comfortable. A teenager wants something affordable.

If you think about it, though, it is even more complicated than that. For example, just about everyone wants a car that is safe. Reliability is pretty important, too. So the reality is, most people want a car that has multiple attributes. Worse still, they sometimes conflict; making one better will make some other ones worse. Mom wants a safe car, but not one that takes half a day to drive to the corner market. Nor does she want to pay a half million dollars for a safe car.

Continue reading “Cover Your Glass: A Lesson in Design Trades”

The Price of Space

Many engineers of a certain age have one thing in common: Their early interest in science and engineering came from watching the US and Russian space programs. To me, regardless of any other benefit from the space program (and there are many), that ability to inspire a future generation of engineers made the entire program worthwhile.

We live in a world where kids’ role models are more likely to be sports or entertainment figures that have regular visits to police stations, jails, and rehab centers. The value of having role models that “do science” is invaluable.

This time of the year is a dark time for NASA missions, though. On January 27, 1967, the Apollo I crew (Grissom, White, and Chaffee) died in a fire. The investigation led to NASA limiting how much Velcro you can use in a cabin and moving away from pure oxygen in the cabin.

Continue reading “The Price of Space”

Hanging Out With Someone Who Walked On The Moon

Lunar dune buggy rides, piloting the most powerful machine made by humankind, stuck thrusters, landing, eating, sleeping, and working on the moon. It does not get any more exciting than the Apollo program! I was recently given the opportunity to sit in on the MIT course, Engineering Apollo: the Moon Project as a Complex System where I met David Scott who landed on the moon as commander of Apollo 15. I not only sat in on a long Q and A session I also was able to spend time with David after class. It is not every day you that you meet someone who has landed on the moon, below are my notes from this experience.

Continue reading “Hanging Out With Someone Who Walked On The Moon”