Neural Networks And MarI/O

June 14, 2015 by Brian Benchoff 30 Comments

Minecraft wizard, and record holder for the Super Mario World speedrun [SethBling] is experimenting with machine learning. He built a program that will get Mario through an entire level of Super Mario World – Donut Plains 1 – using neural networks and genetic algorithms.

A neural network simply takes an input, in this case a small graphic representing the sprites in the game it’s playing, sends that input through a series of artificial neurons, and turns that into commands for the controller. It’s an exceedingly simple neural network – the network that can get Mario through an entire level is less than a dozen neurons – but with enough training, even simple networks can accomplish very complex tasks.

To train the network, or weighting the connections between inputs, neurons, and outputs, [SethBling] is using an evolutionary algorithm. This algorithm first generates a few random neural networks, watches Mario’s progress across Donut Plains 1, and assigns a fitness value to each net. The best networks of each generation are combined, and the process continues for the next generation. It took 34 generations before MarI/O could finish the level without dying.

A few members of the Internet’s peanut gallery have pointed to a paper/YouTube video by [Tom Murphy] that generalized a completely different technique to play a whole bunch of different NES games. While both [SethBling]’s and [Tom Murphy]’s algorithms use certain variables to determine its own success, [Tom Murphy]’s technique works nearly automatically; it will play about as well as the training data it is given. [SethBling]’s algorithm requires no training data – that’s the entire point of using a genetic algorithm.

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Retro Edition: The LAN Before Time

June 12, 2015 by Brian Benchoff 58 Comments

Ethernet has been around since the mid-70s, but if you think it was always Cat5 and 10BaseT, you’d be sorely mistaken. The first ethernet was built with coaxial cable, vampire taps, AUI adapters, and a whole bunch of other network hardware that will make wizened networking veterans cringe. [Matt] had heard about these weird physical layers back when he started building networks in 1997, but he had never seen one. Now it’s an ancient and forgotten footnote in the history of computer networking. Is it possible to build a Thicknet in this modern era? It turns out, yes, it’s possible. It’s not easy, though.

The network [Matt] is building is a true 10Base5, or Thicknet, network. The backbone of this network is a coaxial cable 9.5mm in diameter. [Matt] discovered that while the common belief that Thicknet used RG-8/U cable. This appears to be incorrect, as the connectors for this cable – vampire taps that pierced the insulation and shield of the cable – are designed for cable manufactured by Belden, part number 9880.

[Matt] assembled the cable, vampire taps, AUI cables, and even found a few ISA NICs that would still work with a reasonably modern computer. He even went so far as to build a USB Ethernet adapter with an AUI interface. This impossibly retro device uses a standard USB to 10BaseT Ethernet adapter, with a chip designed to convert 10BaseT to AUI hacked onto a circuit board. That in itself is an incredible piece of engineering, with a handful of power supplies to get the correct 2.5, 3.3, 5, and 12 Volts to the right places.

As far as exercises in computing history go, [Matt] is at the top of his game. In the process of building it, he also figured out why no one uses Thicknet anymore; once it’s in place, you can’t change it, the cable is big, bulky, and the connectors are terrible. Still, it’s an amazing example of how far we’ve come.

Hackaday Retro Edition: The RadioShack Roomba

June 1, 2015 by Brian Benchoff 15 Comments

A few years ago, Roombas — everyone’s favorite robotic trash can — graced the pages of Hackaday with reverence. There was nothing this little robot couldn’t do, save for going up stairs. Roomba hacks have died off since then, and these little trash cans have been swallowed up by dumpsters. It’s all very sad, really.

[Mike] has had one of these Roombas around for a while, sitting in a closet, waiting for someone to make use of it. He recently dug it out, looked it over, and watched the LEDs light up after troubleshooting a problem with the batteries. Then the problem was how to control it.

He had wanted to connect it to a VIC-20, but the handy serial port on the Roomba only accepted baud rates between 19.2k and 57.6k. The VIC-20, with the ancient 6522 VIA, could only bitbang a serial port up to 2400bps. Then the idea hit him. In his closet of ancient technology, [Mike] had a Tandy 102, a slightly upgraded TRS-80 Model 100 that could easily drive a serial port at 19.2k.

When it comes to a mobile retro robotics platform, [Mike] couldn’t have found a better computer. The Tandy 102 has a display, a BASIC interpreter, enough RAM to run a Roomba, and is powered by a few AA batteries. He did need a little bit of level conversion for the serial port, but a MAX232 took care of that easily.

With everything put together, [Mike] had a robot and a computer that is at least as good as the old Heathkit HERO robot. You can check out a video of the Tandy bot below.

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From Scrap To Sword: Casting Pewter

May 31, 2015 by Adam Fabio 17 Comments

[TheBackyardScientist] has been living up to his name, this time by casting a pewter sword in his yard. Pewter is a soft alloy of mostly (85–99%) tin along with copper, antimony and bismuth. Older pewter castings often used lead as well. The great thing about pewter is its low melting point of 170–230 °C. At such low temperatures, pewter can be melted down on a common hot plate. Think of it as an easy way to get into the world of metal casting – no forge required. Of course, anyone who has been splashed with solder will tell you that hot molten metal always deserves a lot of respect.

[BackyardScientist] obtained his metal by hunting the local thrift stores. He used the “lost foam” method of casting, by carving a sword out of styrofoam. The sword was embedded in a 5 gallon bucket of sand with a riser to allow the mold to be filled. The pewter was melted on a cheap hot plate, and poured into the mold. The hot metal melts the foam on contact, simultaneously filling up the cavity left over in the sand mold. [BackyardScientist] was left with a solid pewter sword. It won’t hold an edge, but it is a great illustration of the technique.

Click past the break to see [TheBackyardScientist’s] video.

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How To Tell If You’re Installing Foil Capacitors Backwards

May 20, 2015 by Brian Benchoff 27 Comments

It only takes one mistake to realize electrolytic capacitors have a polarity, but if you’re working with old tube gear, tube amps, or any old equipment with those old orange dip, brown dip, or green dip foil capacitors you also have to watch your polarity. These old caps were constructed with a foil shielding, and there’s always one side of these caps that should always be connected to the chassis ground. If you don’t, you’re going to get interference – not something you want in an amplifier circuit.

Old caps that have long since given up the ghost usually have a black band designating whatever side of the cap the ‘foil ground’ is. This is the side that should be connected to ground. If you look at modern foil caps, you might also see a black band on one side of the cap, which should – if we lived in a just world – also designate the foil ground. This is not always the case.

To properly test foil caps and determine which side should be closer to ground, you can construct a small tester box that’s more or less an h-bridge with a single switch and a pair of alligator clips in the middle. Connect the cap to the clips, put the output of the circuit in your scope, and flick the switch: the direction that has the least amount of interference is the denotes the foil ground of the cap. Replace those old caps in your vintage equipment with a new, correctly oriented cap, and you’re well on your way to having a great sounding amplifier.

Video below.

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Articulated Computer Lamp Lights Up Your Life

May 17, 2015 by Adam Fabio 17 Comments

[Samimy] raided his parts bin to build this articulated lamp (YouTube link) for his computer workstation. Two pieces of aluminum angle form the main body of the lamp. Several brackets are used to form two hinges which allow the lamp to be positioned above [Samimy’s] monitor. The light in this case comes from a pair of 4 watt LED bulbs.

[Samimy] used double nuts on the moving parts to make sure nothing comes loose. The outer nuts are acorns, which ensure no one will get cut on an exposed bit of threaded rod. [Samimy] wired the two bulbs up in a proper parallel mains circuit. The switch is a simple toggle mounted in a piece of Plexiglass on the end of the lamp.

One thing we would like to see on this build is a ground wire. With all that exposed aluminum and steel, one loose connection or worn bit of insulation could make the entire lamp body live.

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Vintage Computers At Maker Faire

May 17, 2015 by Brian Benchoff 6 Comments

It’s no secret that Maker Faire is highly geared toward the younger crowd. This doen’t mean the Faire is completely devoid of the historic; the Bay Area Maker Faire is right in the heart of the beginnings of the computer industry, and a few of the booths are showing off exactly how far computers have come over the last forty years.

[Vince Briel] of Briel Computers has a booth showing off his wares, mostly modern reimaginings of vintage computers. His table is loaded up with replica 1s, a board that’s much smaller but still completely compatible with the Apple I. The MicroKIM made an appearance, but the crown jewel is [Vince]’s Superboard III, a replica of the Ohio Scientific Superboard II. It’s your basic 6502 computer with 32k of RAM, but unlike just about every other modern retrocomputer out there, [Vince] put the keyboard right on the main board.

The switches are Cherry MX, the keys are from WASDkeyboards. [Vince] is actually getting a lot of interest in making modern ASCII keyboards to replace the old and busted boards that came in the home computers of the 70s and 80s. That might be a project [Vince] will release sometime in the future.

The Superboard III

A much, much smaller version of the Altair

The Replica I, fully compatible Apple I replica

MicroKIM

[Jef Raskin], the Swift Card, and the Canon Cat

[Steve Jobs] may have been the father of the Macintosh, but he was, by no means, solely responsible for the Mac. It was a team of people, and when you talk about the UI of the Mac, the first name that should come up is [Jef Raskin].

One of [Jef Raskin]’s finest works was the Swyft Card, an add-on to the Apple II that was basically just a ROM card that had an OS and Forth interpreter on it. The distinguishing feature of the Swyft card was the use of ‘leap’ keys, a simple way to change contexts when using the computer. We’ve seen replicas of the Swyft card before, courtesy of [Mike Willegal] at the Vintage Computing Festival East.

[Dwight Elvey] of the vintage-computer.com forum brought a few extra special items related to [Raskin] and the Canon Cat. The first was a Swyft card installed in an Apple IIe. The second was a prototype Swyft computer, with SERIAL NUMBER 1 printed on a Dymo label and fixed to the case.

The ‘woodie’, as [Dwight] calls it, has two 1.44 MB disk drives, of which half of the disk is actually usable. [Dwight] didn’t take the machine apart, but I’m 99% sure the CRT in it is the exact same tube found in early 9″ Macs.

Also in [Dwight]’s display is a production Swyft computer and a Canon Cat, the final iteration of [Jef Raskin]’s idea of what a text-based computer should be.

The vintage-computer booth also had a few interesting retrocomputers including a Commodore 128D, the Apple made, Bell & Howell branded Apple II, and an Amiga 2000. Right next door was the Computer History Museum, who brought a very kid-friendly storage medium display. Showing a 10-year-old an 8″ disk is fun.