Flash is obsolete and the IBM 5150 is obsolete. Therefore, by the transitive property of algebra, you should be able to run flash games on IBM’s original PC, right? Okay, obviously not — there’s obsolete, and then there’s obsolete — but that didn’t stop [TheRasteri] from trying to bring his favorite scatological humor game to glorious CGA in a slightly not-safe-for-work video.

CGA is really not meant to display the fine details of a 2000s flash game, but [TheRasteri] has some experience with the Amstrad CPC and its demoscene, where they’ve learned to hack the heck out of the same MC6845 CRT controller chip that lives on a CGA card. With a few lines of carefully-crafted assembler, he’s able to swap character height on the fly to create the equivalent of a 160 x 86 pixel window in CGA text mode. That’s probably the most impressive part of this build, but the adventure of vintage-DOS C development on display here is worth watching. He’s using Open Watcom V2 and coding the entire thing as a huge state machine, and tests it on a wide range of DOS machines to catch all the bugs.

While Adobe Flash once enabled a golden age of browser games, we could be on the verge of another thanks to WebAssembly. If you want to hear about programming in C on DOS, we’ve seen a good case made for it.

Back in the day, if one wanted a particular guitar effect one would purchase an effects pedal or “stomp box”, and even a modest collection of them could be an eye-watering investment. A guitar amp chosen for a specific sound could be another huge purchase (and who stops at one?) But if you’ve got a Raspberry Pi kicking around and a bit of free time, PiPedal provides configurable effects, guitar amp emulation, and more.

Things have come a long way in terms of audio processing, and PiPedal is no straightforward application of simple digital filters. We indirectly learned about it from a fellow who used it to experiment with a range of equipment he could in no reality actually afford. He shared his experience in a blog post that left him thinking he might as well sell all his pedals and build the stomp box of his dreams around PiPedal.

PiPedal’s impressive audio engine runs on a Raspberry Pi (or comparable single-board Linux computer) with control and configuration accessed from a mobile device or web browser. It’s expressly designed to seamlessly work whether one is at home, on stage, or in a studio.

The GitHub repository has code and documentation, so check it out. And if you use it as the basis of a project of your own, don’t keep it to yourself! Drop us a note on the tips line because we absolutely want to know all about it.

Many of us will have followed the early history of electronic computing, from the urgent necessities of war, to universities, and then on into the wider world. Most of the firsts in that field are now well known, but there’s one that’s a little obscure. LEO was a commercial development of Cambridge University’s EDSAC that was produced at the behest of J. Lyons and Comapny, one of the UK’s largest mid-20th-century food producers. As such it was the first purpose-built electronic business computer, and since its 75th anniversary is upon us, the Centre for Computing History is holding an event to mark the occasion.

There’s a whole cultural essay to be written about the role of Lyons in twentieth-century Britain, but for Hackaday purposes it should suffice to say that there was little in the way of food production that they didn’t touch. The shops were full of Lyons cakes, biscuits, and tea, and a feature of many towns would have been a Lyons Tea Shop, a budget restaurant. The logistics of such a complex business made a computer of great interest to the company, and after some of its executives learned about ENIAC on a trip to the USA they sought out a machine closer to home. They found the EDSAC, a research computer, and commercialised it as Lyons Electronic Office, or LEO. This spawned a series of machines that lasted into the 1970s, the last one being used by the British Post Office.

It might be difficult to find a LEO in a museum today, but in the National Museum of COmputing at Bletchley you can find the next best thing in their recreation of EDSAC. It’s a decade since we visited, perhaps it’s time for a return.

Header image: Spudgun67, CC BY-SA 4.0.

Laser harps aren’t quite a right of passage, in that not everyone builds them, but it’s likely everyone at least contemplates building one at one time or another. We’re lucky that [Derrick] a.k.a. [DJ Baja Blast] didn’t stop at contemplating, and even luckier that he put together a full write-up for his tricked out laser harp — because this is a fascinating build, with features we’ve never seen in one place before.

First of all, the harp! Lasers, photodiodes, done, right? Not here! [DJ Baja Blast] kept it analog with photoresistors so that he could measure the rise and fall of the voltage as the laser light is occluded by the player’s hands — thus you can moderate the volume via faster, louder and quieter, slower plucks. More unique is the inclusion of an accelerometer. What can you do with an accelerometer in a harp? Well, here it’s being used as a tilt sensor, with the tilt acting as a control to ‘bend’ the note as it sounds, tuning it flat or sharp or altering it any other way you choose to define in software. There’s also an ultrasonic distance sensor so you can do the same thing — or any other thing, there’s no shortage of effects to chose from — theremin-style, and an encoder wheel sits on the side, so that’s five extra inputs beyond selecting a note by blocking a laser diode. Unless you count the optional looper pedal input, or the aux in.

All these inputs are driving a Teensy 4.1 microcontroller, which has the grunt for just about any synthesis or sampling, though right now [DJ Baja Blast] is sticking with the Karplus-Strong string synthesis algorithm. The Teensy can drive an onboard speaker but also offers MIDI out. Eventually he does intend to add more. Last but not least, we cannot forget that he’s plumbed this instrument to hook to a fog machine. Which makes for a visually engaging performance, and probably helps a lot when you’re learning where the laser ‘strings’ are.

The whole thing is handsomely put together with cherry and walnut. Does it sound as good as it looks? Listen to it in action in the demo video below, and judge for yourself! If you want to build your own you can grab the files on GitHub.

This is hardly the first laser harp we’ve seen, or even the first to use a Teensy, but it’s certainly got the most options to spice up a performance. It’s got to be a baja blast to play.

Dirt cheap toy cameras have long been a target for the curious camera hacker, and we’ve seen plenty of lens swaps and other hardware hacks. Until now their internals have remained something of a black box though, so it’s very interesting indeed to see [Spode] breaching the firmware on one and making it run DOOM. Yes, it runs the game, but the value is in opening up this platform.

The Achiles’ heel on this particular camera is its easily updatable firmware, allowing new firmware to be placed upon it with ease. The SoC is an HX3302B which [SpriteTM] has done some work on, so he’s not going in entirely blind. A neat hack to dump the camera’s memory into EXIF data on photos completed the puzzle. He was able to benchmark the thing and find it to be surprisingly powerful, certainly enough for a game from 1993. Doomgeneric looked promising, but first there was the matter of the device’s RAM.

In another clever move he was able to keep only the most-used piece of the doom code in memory and the rest in flash, allowing the game to run. A custom synthesizer completed the experience, and on the write-up there’s a chance to travel back to the early ’90s and hear that music again. All that was left were the controls, and with a few quirks, this thing becomes a playable DOOM console. It’s probably better at that than it is at being a camera.

If you’re hungry for more, we’ve taken a look at similar devices before.

Although not very glamorous, wax motors are a fairly common type of linear actuator. They use the thermal response of waxes and the resulting volumetric expansion or reduction to create a relatively fast, smooth, and highly predictable actuator that can work for decades. They can often be found operating valves and things like the door mechanisms of washing machines. As [BubsBuilds] demonstrates in a recent video, you can even build your own wax motor for very precise control.

Here simple paraffin wax is used, which changes in volume by 1.15 times when it goes from solid to its molten state. Calling it a ‘waxtuator’, [BubsBuilds] characterized this expansion rate over the temperature range between solid and fully molten to make it a controllable actuator. In his experiments, a gap of less than 5 µm was maintained over twelve hours, showing how precise this device can be if you can control the temperature that the wax is kept at.

One major issue is the low conductivity of paraffin wax, which as some commentators remark can be solved by mixing something like fine copper particles into the wax to increase the thermal conductivity. In the shown implementation instead multiple channels in the aluminium block are used, which are melted by a TEC element.

The wax exerts pressure on a working fluid, which then pushes on a hydraulic cylinder that can be used for whatever precise linear actuating task has to be performed. Although initially water was used as a working fluid, this posed many issues with wax-water interface compatibility and vacuum degassing.

Although ethylene glycol makes for a better working fluid, this proved to be its own hassle. With the water-wax version a displacement sensor was thus used to measure and calibrate the whole setup. The electronics used to control the TEC in combination with the current temperature and displacement are a story in itself, but essential for making this device work.

While not something we often see tackled in the DIY space, we’ve covered a few teardowns of commercial units over the years.

It seems fair to say that semiconductor technology has been one of the most influential inventions in human history. Practically overnight it turned human technology from being large, cumbersome and power-hungry into an increasingly sleeker, more power-efficient and much more capable form. It has become practically impossible at this point to imagine modern society without semiconductor technology.

That said, we didn’t always use today’s silicon-based semiconductor technology, and although silicon-based semiconductors are exceedingly versatile and adaptable, they do have their limitations. The past years we have seen for example gallium-nitride semiconductors make big inroads in power switching technology, and more exotic forms like diamond-based semiconductors keep making their tantalizing appearances.

In this article we’ll take a look at how we ended up at silicon as the default for semiconductor technology, as well as why we may want to consider moving to other materials.

Semiconductors

Although semiconductor technology works on very different principles than vacuum tubes and relay-based electromechanical systems, ultimately the goal is the same. This being to make electrons go to certain place when and where you want them to go there. In the case of semiconductors this is achieved through n-type and p-type materials, which are areas in the semiconductor material which display different electron mobility behavior.

The base material is – as the name suggests – a material that falls in between a conductor and an isolator. This conductivity can further be altered by embedding other elements into its crystal matrix, which is generally called ‘doping’. This creates an extrinsic semiconductor, as opposed to the pure, undoped intrinsic semiconductor. This doping process create two distinct types of semiconductor, being the aforementioned n- and p-types.

These letters refer to whether they hold a negative or positive charge, effectively whether this semiconductor material is an acceptor (p-type) or a donor (n-type) of electrons. It’s not required to dope the base material to create both n- and p-type areas, which led to many variations just within the metal-oxide-semiconductor (MOS) family, including the n-type MOSFET-based NMOS, p-type MOSFET-based PMOS and the complementary CMOS that uses both types.

CMOS became the dominant technology by the 1980s to create field-effect transistors (FETs), although the ‘MOS’ part isn’t necessarily technically correct any more as the original aluminium layer can be replaced with polysilicon.

Of course, semiconductor technology didn’t start right off the bat with today’s silicon, dopants and construction methods. The first functional transistor and diode designs are good examples here of where the revolution began, and how things evolved from there.

The First Diode

Although the invention of the point-contact transistor in 1947 is pretty well-known at this point, semiconductor diodes came onto the scene first. The first crucial discovery here was made by German physicist Karl Ferdinand Braun in 1874, when he discovered the asymmetric conduction of electricity in a range of materials involving a metal-semiconductor junction between a metal and types of minerals.

The discovery of this type of junction laid the groundwork first for a practical point-contact diode by the 1930s, using semiconductors ranging from selenium and silicon carbide to germanium and silicon. These were found to be much superior to the thermionic diodes that were first put into commercial use. Especially the push to develop radar and radio technologies during World War 2 drove the development of better semiconductor diodes.

With increased understanding of doping the intrinsic semiconductor material to affect its behavior, it was thus only a matter of time before the point-contact transistor was developed. From there both practical experimentation and a deeper understanding of the underlying electron mobility principles drove innovation forward.

Silicon As Easy Mode

The primary reason why silicon is the most-used semiconductor material today has less to do with it being a good base material and more with it being both plentiful, cheap and easy to process. The silicon dioxide (SiO₂) that forms the pure silicon crystals is the main constituent of sand where it’s called quartz. It will readily melt and can be drawn into very large crystals that can subsequently be cut up into the silicon wafer on which semiconductor circuits can be etched.

Silicon’s band gap is however rather small at 1.14 eV, which means that the correct functioning of circuits created with this semiconductor will cease much sooner with higher temperatures including those generated by the device itself. So-called wide-bandgap semiconductors have a bandgap of >2 eV, which includes the gallium-nitride (GaN) semiconductor which the past years has become a frequent sighting in compact power electronics where being able to run hotter without issues and higher efficiency is considered a big selling point.

GaN’s bandgap is 3.4 eV, which puts it pretty high up in the bandgap rating. In addition to a higher bandgap number, its thermal conductivity is also pretty good at about 230 W·m⁻¹·K⁻¹. These advantages makes it economically feasible to produce GaN components despite the material being harder to process. Which is also the crux of why diamond semiconductors haven’t yet cornered the market.

Before moving on, an interesting note is that germanium has one advantage over silicon despite having an even smaller bandgap. This being that it doesn’t have to be as extremely pure as silicon to work well, which was a benefit especially during the early days of semiconductor technology.

Peak Semiconductor

Although diamond isn’t necessarily the ultimate semiconductor material, its properties makes it look very good indeed. With a bandgap of about 5.6 eV and a thermal conductivity of 900–2,320 W·m⁻¹·K⁻¹ it pretty much destroys both silicon and GaN. The only problem we are facing here is that diamond is an absolute pain in the backside to create large wafers from, not to mention dope the crystal lattice without using the easy ion implantation used for silicon wafers.

Creating diamond wafers requires growing them from seed crystals, rather than just drawing a massive crystal from a vat of molten goo as in the case of silicon. This alone is highly problematic for any large-scale commercialization.

The issue of doping and similar typical semiconductor circuit things being rather hard with diamond is not unique to silicon semiconductor alternatives, which is one reason why the MESFET  field-effect transistor was developed. This drops the insulating oxide layer under the gate, instead using a metal-semiconductor (Schottky) junction.

Such a MESFET design allows for other exotic semiconductor materials like gallium arsenide and silicon carbide, the latter being rather comparable to GaN in terms of bandgap and thermal conductivity, while allowing for very high switching speeds.

An Exciting Future

Despite the occasional bouts of doom-and-gloom stories about the semiconductor industry and issues with scaling and cooling, semiconductor materials like diamond show that there’s still a lot of potential to look forward to. Diamond-based semiconductors could potentially outperform all currently used commercial semiconductor materials, while rapidly moving any waste heat away to whatever cooling solution exists.

Even before said Diamond Age commences, the rise of silicon alternatives like GaN are already showing that despite many decades of breakneck innovation we are hardly at the pinnacle of what is possible. Although making predictions about the future is a fool’s errand at the best of times, it’s good to remain optimistic about such potentially world-changing events like the death of silicon semiconductors in favor of something much better.