Using The GPU From JavaScript

July 17, 2017 by Al Williams 50 Comments

Everyone knows that writing programs that exploit the GPU (Graphics Processing Unit) in your computer’s video card requires special arcane tools, right? Well, thanks to [Matthew Saw], [Fazil Sapuan], and [Cheah Eugene], perhaps not. At a hackathon, they turned out a Javascript library that allows you to create “kernel” functions to execute on the GPU of the target system. There’s a demo available with a benchmark which on our machine sped up a 512×512 calculation by well over five times. You can download the library from the same page. There’s also a GitHub page.

The documentation is a bit sparse but readable. You simply define the function you want to execute and the dimensions of the problem. You can specify one, two, or three dimensions, as suits your problem space. When you execute the associated function it will try to run the kernels on your GPU in parallel. If it can’t, it will still get the right answer, just slowly.

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PLC Vs Arduino Show Down

July 17, 2017 by Al Williams 84 Comments

Hackaday readers don’t need an introduction to the Arduino. But in industrial control applications, programmable logic controllers or PLCs are far more common. These are small rugged devices that can do simple things like monitor switches and control actuators. Being ruggedized, they are typically reasonably expensive, especially compared to an Arduino. [Doug Reneker] decided to evaluate an Arduino versus a PLC in a relatively simple industrial-style application.

The application is a simple closed-loop control of flow generated by a pump. A sensor measures flow for the Arduino, which adjusts a control valve actuator to maintain the specified setpoint. The software uses proportional and integral control (the PI part of a PID loop).

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The Cheapest Meter On Banggood

July 17, 2017 by Al Williams 61 Comments

According to [pileofstuff], he didn’t really need another digital multimeter. However, when he saw a DT-832 meter on Banggood for the princely sum for $4.99 he wondered just what kind of meter you’d get for that price. You can see his conclusions in his recent video (below). He does make it clear, by the way, that he wasn’t paid for the review or given the meter. He just decided to see what $5 would buy in a meter.

Depending on your predisposition to cheap Asian electronics, you may or may not be surprised. After all, for $5 you can’t expect a top-of-the-line lab instrument. The device measures AC and DC voltage, DC amperage, ohms, transistor beta, and has a diode tester and continuity buzzer. It also has some frequency measurement capability. You can’t be too surprised it doesn’t auto range, though. To be fair, although he mentions Banggood as the source of the meter, a quick Google search shows you can get them from all the usual sources, and the price is down to $3.73 as long as you let them ship it from Canada.

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Radiohead’s Greatest Hits For The ZX Spectrum

July 16, 2017 by Al Williams 9 Comments

We’ll admit that only a few of us here at Hackaday are Radiohead fans. However, we all couldn’t help but appreciate their new remastered release of OK Computer. The new release contains some bonus material. At the end of the bonus material is a strange noise that turns out to be a ZX Spectrum Basic program.[OooSLAJEREKooO] managed to find it, play it, and record it for all of us (see video below).

The two minutes of tones might sound unfamiliar to a modern computer user, but back in the day, audio tones were used to communicate over phone lines and to load and save programs via cassette tape recorders. You might be asking yourself: why the ZX Spectrum? Radiohead is from the UK, but that’s not the complete picture. Of all home computers, the ZX Spectrum had a higher effective bit rate when storing data on tape. Basically, it takes less time (and less tape) to put it on a Speccy than a C64 or Apple.

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The Sound Of (Synthesized) Music

July 15, 2017 by Al Williams 7 Comments

What’s an ADSR envelope generator? If you are a big music hacker, you probably know. If you are like the rest of us, you might need to read [Mich’s] post to find out that it is an attack-decay-sustain-release (ADSR) envelope generator. Still confused? It is a circuit used in music synthesis. You can see a demo of the device in the video below.

Before the Altair–which was sort of the first hobbyist computer you could actually buy–electronics magazines were full of music synthesizer projects that had a lot in common with the analog computers of old. A lot of people took that very seriously and then computers took over the collective consciousness and we found musical hackers started working with (digital) computer-based synthesizers. But the old analog synth designs just won’t die. [Mich’s] ADSR is based on an ancient design, and the amount of information and additions he provides makes it worth a read, even if you don’t fancy building one.

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Game Like It Is 1983

July 12, 2017 by Al Williams 33 Comments

The first computer I ever physically saw — I think — was an IBM System/3. You might not remember them. They were business computers for businesses that couldn’t justify a big mainframe. They were “midrange.” Nevermind that the thing probably had the memory and processing speed of the CPU inside my mouse. Time progressed and IBM moved on to the System/3x (for example, the System/32). Next up was the AS/400 and finally the IBM i, which is still in production. Here’s a secret, though, most of the code I’ve seen running on an IBM i dates back to at least the System/3 days and maybe even before that.

If you are interested in history, or midrange computers (which are mainframe-like in their operation), you might want to actually play with a real machine. A quick glance at eBay tells me that you might be able to get something workable for about $1000. Maybe. That’s a bit much. What if you could get time on one for free? Turns out, you can.

The Cloud Option

Head over to PUB400.com and register for an account. This won’t be instant — mine took a day or two. The system is for educational purposes, so be nice and don’t use it for commercial purposes. You get 150MB of storage (actually, some of the documentation says 250MB, and I have not tested it). While you are waiting for your account, you’ll need to grab a 5250 terminal emulator and adjust your thinking, unless you are a dyed-in-the-wool IBM guy.

Even though the IBM i looks like an old 1970’s midrange, the hardware is quite modern with a 64-bit CPU (and the architecture can handle 128 bits) and well-known stability. However, the interface is, well, nostalgic.

Ready…

Depending on your host computer, there are several IBM 5250 terminal programs available. They recommend tn5250 or tn5250j which use Java. However, I installed Mochasoft’s emulator into my Chrome browser. It is a 30-day free trial, but I figure in 30 days I’ll be over it, anyway.

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JPEG Decoding, Arduino Style

July 12, 2017 by Al Williams 32 Comments

When you think of image processing, you probably don’t think of the Arduino. [Jan Gromes] did, though. Using a camera and an Arduino Mega, [Jan] was able to decode input from an Arduino-connected camera into raw image data. We aren’t sure about [Jan’s] use case, but we can think of lots of reasons you might want to know what is hiding inside a compressed JPEG from the camera.

The Mega is key, because–as you might expect–you need plenty of memory to deal with photos. There is also an SD card for auxiliary storage. The camera code is straightforward and saves the image to the SD card. The interesting part is the decoding.

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