First Edition of German Computer Mag is a Blast from the Past

Every once in a while we get nostalgic for the old days of computing. Here, we’re getting nostalgic for a past that wasn’t even our own, but will probably bring a smile to all the German hackers out there. c’t magazine has its first issue available on their website (PDF, via FTP), and it’s worth checking out even if you can’t read a word of German.

ct-adIt’s dated November/December 1983, and you’re definitely hopping in the WABAC machine here. The cover image is a terminal computer project that you’re encouraged to build for yourself, and the magazine is filled with those characteristic early-computer-era ads, many of them for the physical keyboards that you’d need to make such a device. Later on, c’t would provide plans for a complete DIY PC with plotter, one of which we saw still running at the 2015 Berlin Vintage Computer Festival.

The issue is chock-full of code for you to type out into your own computer at home. If you didn’t have a computer, there are of course reviews of all of the popular models of the day; the TRS-80 Model 100 gets good marks. And if you need to buy a BASIC interpreter, there’s an article comparing Microsoft’s MBASIC with CBM’s CBASIC. A battle royale!

ct_mag_computer_bandOther hot topics include modifications to make your ZX81’s video output sharper, the hassle of having to insert a coded dongle into your computer to run some software (an early anti-piracy method), and even a computer-music band that had (at least) a Commodore 64 and a CBM machine in their groovy arsenal.

It’s no secret that we like old computers, and their associated magazines. Whether you prefer your PDP-11’s physical or virtual, we’ve got you covered here. And if your nostalgia leans more Anglophone, check out this Byte magazine cover re-shoot.

Rubber Tanks and Sonic Trucks: The Ghost Army of World War II

Winston Churchill once told Joseph Stalin “In wartime, truth is so precious that she should always be attended by a bodyguard of lies”. During World War II, the power of these bodyguards, in the form of military deception, became strikingly apparent. The German military was the most technologically advanced force ever encountered. The Germans were the first to use jet-powered aircraft on the battlefield. They created the enigma machine, which proved to be an extremely difficult system to break. How could the Allies possibly fool them? The answer was a mix of technology and some incredibly talented soldiers.

The men were the 23rd Headquarters Special Troops, better known as the Ghost Army. This unit was the first of its kind specifically created to deceive the enemy. Through multiple operations, they did exactly that. These 1100 soldiers created a diversion that drew German attention and gunfire to them, instead of the thousands of Allied troops they were impersonating.

The Ghost Army consisted of 4 distinct groups:

  • The 406th Engineer Combat Company Special were 166 “regular” soldiers – these men handled security, construction, and demolition.
  • 603rd Camouflage Engineers were the largest group at 379. As the name implies, the 603rd was created to engineer camouflage. 
  • 3132 Signal Service Company consisted of 145 men in charge of half-tracks loaded down with massive 500 watt speakers which could be heard for 15 miles. 
  • The Signal Company Special Formerly the 244th signal company, The 296 men of the Signal Company Special handled spoof radio communications.  The Germans heavily relied on captured and decoded radio messages to determine the Allies’ next move.

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Better Networking With A Macintosh Classic

While it may not be the case anymore, if you compare a Mac and a PC from 1990, the Mac comes out far ahead. PCs suffered with DOS, while the Mac enjoyed real, non-bitmapped fonts. Where a Windows PC required LANMAN to connect to a network, the Mac had networking built right into every single machine. In fact, any Mac from The Old Days can use this built-in networking to connect to the Internet, but most old Mac networking hacks have relied on PPP or other network to serial conversion. [Pierre] thought there was an incomplete understanding in getting old Macs up on the Internet and decided to connect a Mac Classic to the Internet with Apple’s built-in networking.

Since the very first Macintosh, Apple included a simple networking protocol that allowed users to share hard drives, folders, and printers over a local network. This networking setup was called LocalTalk. It wasn’t meant for internets or very large networks; the connection between computers was basically daisy chained serial cables and later RJ-11 (telephone) cables.

LocalTalk stuck around for a long time, and even now if you need to do anything with a Mac made in the last century, it’s your best bet for file transfer. Because of LocalTalk’s longevity, routers and LocalTalk to Ethernet adapters can be found fairly easily. The only problem is finding a modern device that speaks both TCP/IP and LocalTalk. You can’t use a new Mac for this; LocalTalk has been gone from OS X since Snow Leopard. You can do it with a Raspberry Pi, though.

With a little bit of futzing about with MacTCP and a few other pieces of software from 1993 or thereabouts, [Pierre] can even get his old Mac Classic online. Of course the browsers are all horribly outdated (making the Hackaday retro edition very useful), but [Pierre] was able to load up It takes a while with an 8MHz CPU and 4MB of RAM, but it does get the job done.

You can check out [Pierre]’s demo video below.

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Adding A Second Drive To A Forgotten Commodore

Commodore would never release a laptop, or really much of anything resembling the chunky luggable portable computers of the 1980s. This doesn’t mean a ‘Commodore LCD’ wasn’t designed – it’s sitting in [Bil Herd]’s basement. Of the entire Commodore lineup, the only computer that could remotely be called ‘portable’ is the SX-64, the ‘executive’ version that came with a built-in 5″ monitor, the usual C64 circuitry, one floppy drive, and an empty hole that could obviously hold a second floppy drive. Something must be done about that missing floppy drive, and it only took thirty years for someone to do something about it.

While the conversion requires mucking around in an already tight enclosure, the parts for this conversion are readily available thanks to a few people trying to repair an SX-64, giving up, and parting the whole thing out on eBay. These parts include the 1541 controller relabeled as the ‘FDD’ board in the SX-64, and of course the floppy drive itself. With the right teardown guide, putting the new drive in this old computer isn’t that hard; just remember to cut a jumper to assign the new drive a number other than 8.

The missing floppy drive of the SX-64 is what happens when marketing is put in charge of engineering. There were a few of these dual drive Commodore luggables back in ’83, and we have the computer magazine clippings to prove it. The official story is the power supply wasn’t beefy enough to handle the second drive. This mod, though, seems to work well enough, albeit with a distinct lack of somewhere to store a few floppies.

Find yourself getting sentimental while reading about this great hardware? Keep those feelings going by listening to [Bil] recount some stories from his time at Commodore.

Turning a Pi Into a PDP

There’s no better way to learn how to program a computer than assembly, and there’s no better way to do assembly than with a bunch of blinkenlights and switches. Therefore, the best way to learn programming is with a PDP-11. It’s a shame these machines are locked up in museums and the garages of very cool people, but you can build your own PDP-11 with a Raspberry Pi and just a few extra components.

[jonatron] built his own simulated version of the PDP-11 with a lot of LEDs, a ton of switches, and a few 16-bit serial to parallel ICs. Of course the coolest part of any blinkenlight simulator are the front panel graphics, and here [jonatron] didn’t skimp. He put those switches and LEDs on a piece of laser cut acrylic with a handsome PDP11 decal. The software comes with a load of compiler warnings and doesn’t run anything except for very simple machine code programs. That’s really all you can do with a bunch of toggle switches and lights, though.

If this project looks familiar, your memory does not deceive you. The PiDP-8/I was an entry in this year’s Hackaday Prize and ended up being one of the top projects in the Best Product category. We ran into [Oscar], the creator of the PiDP-8, a few times this year. The most recent was at the Hackaday SuperConferece where he gave a talk. He’s currently working on a replica of the king of PDPs, the PDP-11/70.

Video below.

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Esoteric Actuators

Motors are everywhere; DC motors, AC motors, steppers, and a host of others. In this article, I’m going to look beyond these common devices and search out more esoteric and unusual electronic actuators that might just find a place in one of your projects. In any case, their mechanisms are interesting in their own right! Join me after the break for a survey of piezo, magnetostrictive, magnetorheological, voice coils, galvonometers, and other devices. I’d love to hear about your favorite actuators and motors too, so please comment below!

Piezo actuators and motors

The flexing of a piezo buzzer from arcbotics

Piezoelectric materials sometimes seem magic. Apply a voltage to a piezoelectric material and it will move, as simple as that. The catch of course is that it doesn’t move very much. The piezoelectric device you’re probably most familiar with is the humble buzzer. You’d usually drive these with less than 10 volts. While a buzzer will produce a clearly audible sound you can’t really see it flexing (as it does shown above).

To gauge the motion of a buzzer I recently attempted to drive one with a 150 volt piezo driver, this resulted in a total deflection of around 0.1mm. Not very much by normal standards!

The PiezoMotor LEGS actuator “walks” along a rod, pushing it as it goes.

For some applications however resolution is of primary interest rather than range of travel. It is here that piezo actuators really shine. The poster-boy application of piezo actuators is perhaps the scanning probe microscope. These often require sub-nanometer accuracy (less than 1000th of 1000th of 1 millimeter) in order to visualize individual atoms. Piezo stacks are ideal here (though hackers have also used cheap buzzers!).

Sometimes though you need high precision over a larger range of travel. There are a number of piezo configurations that allow this. Notably Inchworm, “LEGS”, and slip-stick actuators.

The PiezoMotor LEGS actuator is shown to the above. As noted, Piezos only produce small (generally sub-millimeter) motion. Rather than using this motion directly, LEGS uses this motion to “walk” along a rod, pushing it back and forth. The rod is therefore moved, in tiny nanometer steps. However, piezos can move quickly (flexing thousands of times a second). And the LEGS (and similar Inchworm actuator) allows relatively quick, high force, and high resolution motion.


The tablecloth trick (yes this one’s fake, the kid is ok don’t worry. :))

Another type of long travel piezo actuator uses the “stick-slip phenomenon”. This is much like the tablecloth magic trick shown above. If you pull the cloth slowly there will be significant friction between the cloth and this crockery and they will be dragged along with the cloth. Pull it quickly and there will be less friction and the crockery will remain in place.

This difference between static and dynamic friction is exploited in stick-slip actuators. The basic mechanism is shown in the figure below.

Motion caused by a stick-slip motor

When extending slowing a jaw rotates a screw, but if the piezo stack is compressed quickly the screw will not return. The screw can therefore be made to rotate. By inverting the process (extending quickly, then compressing slowly) the process is reversed and the screw is turned in the opposite direction. The neat thing about this configuration is that it retains much of the piezo’s original precision. Picomotors have resolutions of around 30 nanometer over a huge range of travel, typically 25mm, they’re typically used for optical focusing and alignment and can be picked up on eBay for 100 dollars or so. Oh and they can also be used to make music. Favorites include Stairway to Heaven, and not 1 but 2 versions of Still Alive (from Portal). Obligatory Imperial March demonstration is embedded here:

There are numerous other piezo configurations, but typically they are used to provide high force, high precision motion. I document a few more over on my blog.

Magnetostrictive actuators

Magnetostriction is the tendency of a material to change shape under a magnetic field. We’ve been talking about magnetostriction quite a lot lately. However much like piezos it can also be used for high precision motion. Unlike piezos they require relatively low voltages for operation and have found niche applications.

Magnetorheological motion

Magnetorheological (MR) fluids are pretty awesome! Much like ferrofluids, MR fluids respond to changes in magnetic field strength. However, unlike ferrofluids it’s their viscosity that changes.

MRfluidThis novel characteristic has found applications in a number of areas. In particularly the finishing of precise mirrors and lens used in semiconductor and astronomical applications. This method uses an electromagnet to change the viscosity of the slurry used to polish mirrors, removing imperfections. The Hubble telescope’s highly accurate mirrors were apparently finished using this technique (though hopefully not that mirror). You can purchase MR fluid in small quantities for a few hundred dollars.

Electrostatic motors

While magnetic motors operate through the attraction and repulsion of magnetic fields, electrostatic motors exploit the attraction and repulsion of electric change to produce motion. Electrostatic forces are orders or magnitude smaller that magnetic ones. However they do have niche applications. One such application is MEMS motors, tiny (often less than 0.01mm) sized nanofabricated motors. At these scales electromagnetic coils would be too large and specific power (power per unit volume) is more important than the magnitude of the overall force.

Voice coils and Galvanometers

The voice coil is your basic electromagnet. They’re commonly used in speakers, where an electromagnet in the cone reacts against a fixed magnet to produce motion. However voice coil like configurations are used for precise motion control elsewhere (for example to focus the lens of an optical drive, or position the read head of a hard disc drive). One of the cooler applications however is the mirror galvanometer. As the name implies the device was originally used to measure small currents. A current through a coil moved a rod to which a mirror was attached. A beam of light reflect off the mirror and on to a wall effectively created a very long pointer, amplifying the signal.

These days ammeters are far more sensitive of course, but the mirror galvanometer has found more entertaining applications:

High speed laser “galvos” are used to position a laser beam producing awesome light shows. Modern systems can position a laser beam at kilohertz speeds, rendering startling images. These systems are effectively high speed vector graphic like line drawing systems, resulting in a number of interesting algorithmic challenges. Marcan’s OpenLase framework provides a host of tools for solving these challenges effectively, and is well worth checking out.

In this article I’ve tried to highlight some interesting and lesser known techniques for creating motion in electronic systems. Most of these have niche scientific, industrial or artistic applications. But I hope they also also offer inspiration as you work on your own hacks! If you have a favorite, lesser known actuator or motor please comment below!

[Cody] Takes us From Rock To Ring

[Cody Reeder] had a problem. He wanted to make a ring for his girlfriend [Canyon], but didn’t have enough gold. [Cody and Canyon] spent some time panning for the shiny stuff last summer. Their haul was only about 1/3 gram though. Way too small to make any kind of jewelry. What to do? If you’re [Cody], you head up to your silver mine, and pick up some ore. [Cody] has several mines on his ranch in Utah. While he didn’t go down into the 75 foot deep pit this time, he did pick up some ore his family had brought out a few years back. Getting from ore to silver is a long process though.

splattersFirst, [Cody] crushed the rock down to marble size using his homemade rock crusher. Then he roasted the rock in a tire rim furnace. The ore was so rich in lead and silver that the some of the metal just dropped right out, forming splatters on the ground beneath the furnace. [Cody] then ball milled the remaining rock to a fine powder and panned out the rest of the lead. At this point the lead and silver were mixed together. [Cody] employed Parks process to extract the silver. Zinc was added to the molten lead mixture. The silver is attracted to the zinc, which is insoluble in lead. The result is a layer of zinc and silver floating above the molten lead. Extracting pure silver is just a matter of removing the zinc, which [Cody] did with a bit of acid.

Cody decided to make a silver ring for [Canyon] with their gold as the stone. He used the lost wax method to create his ring. This involves making the ring from wax, then casting that wax in a mold. The mold is then heated, which burns out the wax. The result is an empty mold, ready for molten metal.

The cast ring took a lot of cleanup before it was perfect, but the results definitely look like they were worth all the work.

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