Blowing The Dust Off Of An IBM AS/400 Server

January 13, 2019 by 112 Comments

If you’ve never seen an IBM AS/400 machine, don’t feel bad. Most people haven’t. Introduced in 1988 as a mid-range server line, it used a unique object-based operating system and was geared specifically towards business and enterprise customers. Unless you’re a particularly big fan of COBOL you probably won’t have much use for one today, but that doesn’t mean they aren’t worth playing around with if the opportunity presents itself.

So when a local IT company went belly up and was selling their old hardware, including a late 90’s era IBM AS/400e Series, [Rik te Winkel] jumped at the chance to take this unique piece of computing history home. He knew it was something of a risk, as maintenance and repair tasks for these machines were intended to be done by IBM certified technicians rather than the DIYer, leaving little in the way of documentation or even replacement parts. But in the end it worked out, and best of all, he documented the successful process of dragging this 90’s behemoth into the blinding light of the twenty-first century for all the world to see.

After getting the machine home and sitting through its thirty minute boot process, [Rik] was relieved to see the code 01 B N pop on the server’s display. This meant the system passed all the internal checks and was ready to go, he just had to figure out how to talk to the thing. Built to be a pure server, the machine didn’t offer any video output so he’d have to log into it over the network.

[Rik] noted that there was no new DHCP entry in his router for the server, but of course that was hardly surprising as the machine would have certainly had a static IP when it was in use. So he shut the server down, plugged it directly into his laptop’s Ethernet port, and watched the output of Wireshark as it went through its arduous boot sequence. Eventually he started to pick up packets coming from the IP address 10.10.10.9, and he had his target.

There are a few clients out there that allow you to remotely log into an AS/400, so he downloaded one and pointed it to the server’s IP. He was surprised to see the operating system was apparently in Dutch, but at least he was in. He tried a few common usernames and passwords, helped along by the fact that this OS from a somewhat more innocent era will actually tell you if you have the username right or wrong, and eventually managed to hack the Gibson with the classic admin/admin combo.

So he was in, but now what? [Rik] decided that he couldn’t truly call this machine bested until he could pull up the Hackaday Retro Edition, so he started work on writing a program to let him pull down the page directly on the AS/400 in IBM’s proprietary Report Program Generator (RPG) programming language. You know, as one does. He didn’t quite feel up to writing a whole HTML parser, but he got as far as generating a HTTP GET request, downloading the page’s source, and opening it up as a local file. That’s good enough for us.

Our very own [Al Williams] documented his adventures poking around an Internet-connected AS/400 machine, which might serve as a helpful primer if you ever find one of these delightfully oddball computers kicking around the local recycling center.

Hot Glue Makes These Segments Glow

January 13, 2019 by 14 Comments

It’s safe to say that hot-melt glue is a staple of the projects we see here at Hackaday. There won’t be many readers who don’t have a glue gun, and a blob of the sticky stuff will secure many a project. But it’s not so often we see it used as an integral component for a property other than its stickiness, so [DusteD]’s reaction timer project is interesting for having hot glue as a translucent light guide and diffuser for its LED seven-segment display.

The timer is simple enough, being driven by an Arduino board, while the display is pre-formed into the 3D-printed case. The hot glue fills the enclosures behind each segment, and after several experiments it was found that the best filling method was from behind against a piece of Kapton tape. The LEDs were wired into a common cathode array, and along with the arcade-style button and the Arduino the whole fitted neatly in the box. You can see the result in action in the video below the break.

Of course, this display is unusual for its use of hot glue, but not unique. We’ve seen a different take on a hot glue light pipe display before.

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DIY Guided Telescope Mount Tracks Like A Barn Door

January 12, 2019 by 8 Comments

Astrophotography is an expensive hobby. When assembling even a basic setup consisting of a telescope, camera, guiding equipment and mount, you can easily end up with several thousand dollars worth of gear. To reduce the monetary sting a little, [td0g] has come up with an innovative homebrew mount and guiding solution that could be assembled by almost any dedicated amateur, with the parts cost estimated around $100. The accuracy required to obtain high-quality astrophotographs is quite demanding, so we’re impressed with what he’s been able to achieve on a limited budget.

The inspiration for this design comes from an incredibly simple star tracking device known as a barn-door tracker, or Haig mount. Invented by George Haig in the 1970’s, this mount is essentially nothing more than a hinge aligned with the Earth’s axis of rotation. A threaded rod or screw, turned at a constant rate, is used to slowly open the hinge so that a mounted camera tracks the apparent motion of the heavens. As a result, long exposures can show pinpoint images of stars and sharp details of deep-sky objects, instead of curved star trails. [td0g] adapted this technique to drive a more traditional telescope mount, using barn-door-like drive screws on both the right ascension and declination axes. A pair of NEMA 17 stepper motors drive 4-mm pitch Acme threaded rods through toothed pulleys 3D printed from PETG.

Speaking of 3D-printed parts, this build is a good example of judicious use of the technology: where metal parts are warranted, metal parts are used, and printed plastic is relegated to those places where it can adequately do the job. [td0g] has placed the STL files for the printed parts on Thingiverse in case you want to replicate the drive.

The non-linear relationship between the threaded rod rotation and right ascension drive rate usually limits the length of exposure you can reasonably achieve with a barn-door tracker. To adjust for this, [td0g] created a lookup table in firmware to compensate the drive and allow longer exposures. He mentions that the drive will operate for three hours before it hits the end of the screw’s travel and needs to be reset, but if he can manage three hour exposures, his skies must be much darker than ours!

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The Coco-Nutcracker

January 12, 2019 by 10 Comments

Coconut is a delicious and versatile food but if you’ve ever tried to open one you know they can be a hard nut to crack. Those of us who live in the tropics where they are common might reach for a machete, drill, or saw to open them, which is often a messy and sometimes dangerous ordeal. Realizing that a coconut is just a large nut with a shell like any other, [Paul] of [Jackman Works] decided to build a nutcracker big enough to crack a coconut, which turns out to be almost exactly human-sized.

The nutcracker is built almost entirely out of reclaimed wood. Several rings made of many blocks of wood were constructed on the table saw before being glued and clamped together. Once the rings were stacked and glued to each other, [Paul] put them on a lathe to get a smooth finish. Then the arms, legs, body, and head were all assembled. The actual nutcracking mechanism is one of the few metal parts in this build, a long threaded rod which is needed to handle the large forces required for cracking the coconut.

Once the finishing touches were put on the nutcracker, including boots, a beard, some hair, and of course a pom-pom for his hat, [Paul] successfully tested it by cracking a coconut open. This build is exceptionally high quality and is definitely worth scrolling through. He runs a wood shop in DC where he builds all sorts of interesting things like this, including a giant wooden utility knife.

The Clementine Spacecraft

Preventing Embedded Fails With Watchdogs

January 12, 2019 by 24 Comments

Watchdog timers are an often overlooked feature of microcontrollers. They function as failsafes to reset the device in case of a software failure. If your code somehow ends up in an infinite loop, the watchdog will trigger. This is a necessity for safety critical devices. If the firmware in a pacemaker or a aircraft’s avionics system gets stuck, it isn’t going to end well.

In this oldie-but-goodie, [Jack Ganssle] provides us with a great write up on watchdog timers. This tells the story of a failed Clementine spacecraft mission that could have been saved by a watchdog, and elaborates on the design and implementation of watchdog techniques.

If you’re designing a device that needs to be able to handle unexpected failures, this article is definitely worth a read. [Jack] explains a lot of traps of using these devices, including why internal watchdogs can’t always be trusted and what features make for a great watchdog.

Thanks to [Jan] for the tip!

Addressable 7-Segment Displays May Make Multiplexing A Thing Of The Past

January 12, 2019 by 52 Comments

[Sean Hodgins] has a knack for coming up with simple solutions that can make a big difference, but this is one of those “Why didn’t I think of that?” things: addressable seven-segment LED displays.

[Sean]’s design is basically a merging of everyone’s favorite Neopixel RGB LED driver with the ubiquitous seven-segment display. The WS2811 addressable RGB driver chip doesn’t necessarily have to drive three different color LEDs – it can drive three segments of the same display. With three of the chips on a single board, all seven segments plus the decimal point of a display can be controlled over a single data line. No more shift registers, no more multiplexing. And as a nice touch, individual displays can be ganged together with connectors on the back of each module. [Sean] has some code to support the display but is looking for someone to build a standalone library for it, so you might want to pitch in. Yes, he plans to sell the boards in his shop, but as with all his projects, this one is open source and everything you need to build your own is up on GitHub. The brief video below shows a few daisy-chained displays in action.

Like many of [Sean]’s designs, including this Arduino rapid design board, this is a simple way to get a tedious job done, and it wrings a lot of functionality from a single IO pin.

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Electromagnetic 7-Segment Display Easy On The Eyes AND The Ears

January 12, 2019 by 21 Comments

We love electromagnetic displays: take the modern look of a digital readout, combine with the low-tech coil mechanism that you theoretically could create yourself, add a dash of random clacking sounds, and what’s not to like? Evidently, [Nicolas Kruse] shares our affection for these displays, because he’s taken it beyond theory and created a 7-segment magnetically-actuated display from scratch.

The display is 3D-printed, as you would expect these days. Each segment contains a small neodymium magnet, and each coil a 1 mm iron core for flux concentration. The coils are driven with a 1.6 A peak current, causing the segments to flip in less than 10 ms. [Nicolas] provides STL files for the display base, segments, and spools so you can print your own display. He’s also released the schematics and code for the driver, which uses an ATtiny44 to drive the coils through N- and P-channel MOSFETs. Initially designed to drive a passive 4×7 matrix of displays, the driver couldn’t quite manage to flip one segment without affecting its neighbors. However, for a single display, the driver works fine. We hope he figures out the matrix issue soon, because we really want to see a clock made with these displays.

You can see (and hear) a short video of the display in action after the break. The clacking does not disappoint!

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