Doing It With Fewer Bytes Than Bill Gates

March 24, 2017 by Jenny List 29 Comments

The MITS Altair 8800 occupies a unique place in computing history as the first commercially succesful microcomputer for personal rather than business use. It is famous as the platform upon which the first Microsoft product ran, their first BASIC interpreter.

[Josh Bensadon] has an Altair 8800, and became intrigued by its bootloader. The simplest method of programming the machine is through binary using a set of switches on the front panel, and he remarks that there should be a warning in the manual: “fingers will get sore after repeated use of the small switches on the ALTAIR”.

In the Altair manual there are two listings, one 21 byte, and another in 20 bytes. Bill Gates is on record as saying that their first effort was 46 bytes long, but with more work he managed to create one in 17 bytes. Now [Josh] has beaten that, he’s created an Altair 8800 bootloader in only 14 bytes.

His write-up goes into great detail about how those bytes are shaved off, and provides us with a fascinating insight into the 8800’s architecture. Even if your 8-bit assembler is a little rusty, it’s a fascinating read.

We’ve featured Altair-inspired projects many times here at Hackaday, but rarely the real thing. This Altair PC case with the ability to emulate the original was rather a nice idea, as was this Altair front panel project. If you want the joy without the heartache though, there is an online emulator.

Magsafe 1 To Magsafe 2 The Cheap Way

March 24, 2017 by Lewin Day 28 Comments

[Klakinoumi] wanted to use their Magsafe 1 charger from 2007 with their newer Macbook Pro Retina from 2012 — but it had a Magsafe 2 port. There were a few options on the table (buy an adapter, buy a new charger, cry) but those wouldn’t do. [Klakinoumi] went with the brute force option of grinding a Magsafe 1 charger to fit Magsafe 2.

Based on the existence of passive adapters that allow Magsafe 1 chargers to work with newer laptops, we’d assume that the older chargers are probably electrically similar to the newer models. That said, it’s not our gear and we’d definitely be checking first.

With that out of the way, it’s a simple enough modification — grind away the Magsafe 1’s magnet until it fits into a Magsafe 2 port. It really is that easy. The spring-loaded pins all seem to line up with the newer port’s pads. [Klakinoumi] reports it worked successfully in their tests with 2012, 2014 and 2015 Macbooks but that it should be attempted at your own risk — good advice, as laptops ain’t cheap.

When doing this mod, consider taking care not to overheat the connector during grinding. You could both melt plastic parts of the connector, or ruin the magnet by heating it past its Curie point.

Interested in the protocol Magsafe speaks over those little golden pins? Find out here.

Adding Buttons To The ESP-12 – The Cheat Way

March 23, 2017 by Lewin Day 14 Comments

[sorki] had an ESP-12F and wanted to play with nodeMCU, but found they were lacking buttons for reset & flash. We’ve all been there – mucking about with a project on a breadboard, trying to save the time required to solder up a button by shorting pins with wire or bending component legs to touch. This either doesn’t work or ends up bricking the microcontroller when it inevitably goes wrong. [Buger] found a tidier solution to adding buttons to the ESP-12F with the minimum of effort.

It’s the spirit of deadbug applied to buttons. One side of a piece of wire is soldered to the pin needing to be pulled down. Component leg offcuts are ideal for this. The other end of the wire is bent up and left to float over the metal shield of the ESP-12, which is connected to ground. When you want the pin to go low, press the wire into the shield, grounding it. Let it go, and the pin returns high again, assuming your pullup resistors are all in order.

It’s a quick hack that’s much more robust than trying to hold two ends of a piece of hookup wire in place. It’s also still easier than trying to find a tactile switch solder leads to, and you don’t end up having it hanging off the board either.

For deadbug construction taken to an impressive conclusion, check out this clock built out of discrete components.

[Thanks to Richard Marko for the tip!]

Usborne Release More 1980s Computer Books

March 20, 2017 by Jenny List 32 Comments

Children of the 1980s who had an interest in technology were lucky indeed. As well as the first generations of home computers at their disposal they had the expectation to program them, something which the generation that followed had lost.

Traditional children’s publishers enthusiastically embraced the home computer boom, and probably for the only time in history there were books aimed at children covering subjects like machine code, or interfacing to microprocessors.

Kid's books were better when we were young! Usborne(Fair use) — Kid’s books were better when we were young! Usborne(Fair use)

If you are British, the most memorable of these books came from Usborne Publishing. Their format of colourful cartoons and easy to digest layout have made them something of a cult object among the now-grown-up generation who first received them, and Usborne themselves have cleverly exploited their heritage to promote their current offerings by releasing some of them as PDFs. And now, to promote their latest title, “Coding For Beginners Using Python”, they’ve released five more (scroll down to see). Titles are “Practice Your BASIC”, “Better BASIC”, “Computer Controlled Robots”, “Experiments With Your Computer”, and “Keyboards & Computer Music”, which join the fifteen they’ve already released.

Obviously they are heavily based around the microcomputers of the 1980s, but of course for most Hackaday readers that will be their chief attraction. Either way they’re an interesting read, and should you happen to have a few old micros lying around then maybe you could have a go at some of the projects.

If the BASIC listings are a little foreign to you, might we suggest some places to find BASIC information.

Dumpster Dive Speaker Results In Tube Amplifier

March 18, 2017 by Anool Mahidharia 14 Comments

[Michael Wiebusch] found the leftovers of a wrecked vintage tube radio in a pile of electronics junk. Unfortunately, he could not recover any vacuum tubes in it. And to his dismay, it didn’t even have the output transformer, which he figured would have been useful in a guitar amplifier project. The output transformer is not easy to come by nowadays, so he was hoping to at least score that item for his future build. All he could dig out from his dumpster find was a pair of speakers and he ended up building nice Output-Transformer-Less Tube Guitar Amplifier around them.

Valve output stages are generally high-impedance which means they cannot be directly interfaced to low impedance speakers. An impedance matching output transformer is thus used to interface the two. Back in the day when valves were still the mainstay of audio electronics, many cheap amplifier designs would skimp on the output transformer to save cost, and instead use high impedance speakers connected directly to the amplifier output.

[Michael] found a nice reference design of an OTL amplifier for a 620 ohm single speaker. He decided to use the same design but because these speakers were about 300 ohm each, he would have to wire his two speakers in series. At this point, he decided to make his build useful as a proper guitar amplifier by adding a preamplifier stage replicated from another design that he came across. A regular halogen lamp 12V transformer takes care of the heater power supply for all the tubes, and a second, smaller 12V transformer is wired backwards to provide the 300V needed for the plate supply.

The final result is pretty satisfactory, considering that it all started with just a pair of junked speakers. Check out the result in the video after the break.

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Line Follower Has Lots Of Recycled Parts, But Zero Brains

March 18, 2017 by Donald Papp 20 Comments

Line Followers are a tried-and-true type of robot; both hardware and software need to be doing their job in harmony in order to be successful at a clearly defined physical task. But robots don’t always have microcontrollers and software, as [Mati_DIY]’s zero programming analog line follower demonstrates.

For readers used to seeing a Raspberry Pi or Arduino in almost everything, an analog robot whose “programming” exists only as a harmony between its discrete parts can be an eye-opener as well as an accessible project. A video of the robot in action is embedded below.

[Mati_DIY]’s design uses two CNY70 reflective sensors (which are essentially infrared emitter/phototransistor pairs) and an LM358 dual op-amp. Together, the sensors act as two near-sighted eyes. By using the output of each sensor to drive a motor via a transistor, the presence or absence of the black line is directly and immediately reflected by the motion of the attached motor. The more black the sensor sees, the more the motor turns. Electrically, that’s all that happens; but by attaching the right sensor to the left motor and the left sensor to the right motor, you get a robot that always tries to keep the black line centered under the sensors. Playing with the spacing of the motors and sensors further tweaks the performance.

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There’s A Mew Underneath The Truck Next To The SS Anne

March 17, 2017 by Brian Benchoff 26 Comments

Before we dig into this, I need to spend a paragraph or two conveying the knowledge of a twelve-year-old in 1996. Of course, most Hackaday readers were twelve at least once, but we’re just going to do this anyway. The payoff? This is an arbitrary-code-execution virus for Pokemon, and maybe the most amazing Game Boy hack of all time.

In the first generation of Pokemon games, there is a spectacularly rare Pokemon. Mew, the 151st Pokemon, could learn every move in the game. It was a psychic type, which was overpowered in the first gen. You could not acquire a Mew except by taking your Game Boy to a special event (or to Toys R Us that one time). If someone on the playground had a Mew, they really only had a GameShark.

There was a mythos surrounding Mew. Legend said if you went to the SS Anne and used Strength to move a truck sprite that appeared nowhere else in the game, a Mew would appear. Due to the storyline of the game, you didn’t have the ability to get to this truck the first time you passed it. However, if you started a new game – thus losing all your progress and your entire roster of Pokemon – you could test this theory out. Don’t worry, you can just trade me all your good Pokemon. I’ll give them back once you have a Mew. Screw you, Dylan. Screw you.

Now the Mew truck trick is real. You can do it on a copy of Red or Blue on an original Game Boy. If this hack existed in 1998, kids would have lost their god damned minds.

The basis for this hack comes from [MrCheeze], who created a ‘virus’ of sorts for the first generation of Pokemon games. Basically, given the ability to manually edit a save file, it is possible to replicate this save file over a Game Link cable. The result is a glitchy mess, but each Pokemon game has the same save file when it’s done.

Combine this virus with arbitrary code execution, and you have something remarkable. [MrCheeze] created a save file that allows you to move the truck next to the SS Anne. When the truck is moved, a Mew appears. It’s exactly what everyone was talking about over the sound of their sister’s Backstreet Boys marathon.

The new ‘Mew Truck virus’ is not as glitchy as the first attempt at a self-replicating save file. In fact, except for the music glitching for a few seconds, nothing appears abnormal about this Pokemon virus. It’s only when the Mew truck trick is attempted does something seem weird, and it’s only weird because we know it shouldn’t happen. Combine the self-replicating nature of this virus, and you have something that would have drawn the attention of Big N. This is a masterpiece of Pokemon-based arbitrary code execution and a hack that may never be equaled.

You can check out the video below.

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