2025-12-31 00:30:00
The USB port which first appeared on our computers some time in the mid-1990s has made interfacing peripherals an easy task, save for the occasional upside down connector. But in the days before USB there were a plethora of plugs and sockets for peripherals, often requiring their own expansion card. Among these were mice, and [Robert Smallshire] is here with a potted history of the many incompatible standards which confuse the retrocomputing enthusiast to this day.
The first widely available mice in the 1980s used a quadrature interface, in which the output from mechanical encoders coupled to the mouse ball is fed directly to the computer interface which contains some form of hardware or microcontroller decoder. These were gradually superseded by serial mice that used an RS-232 port, then PS/2 mice, and finally the USB variant you probably use today.
Among those quadrature mice — or bus mice, as early Microsoft marketing referred to them — were an annoying variety of interfaces. Microsoft, Commodore, and Atari mice are similar electrically and have the same 9-pin D connector, yet remain incompatible with each other. The write-up takes a dive into the interface cards, where we find the familiar 8255 I/O port at play. We’d quite like to have heard about the Sun optical mice with their special mouse pad too, but perhaps their omission illustrates the breadth of the bus mouse world.
This piece has certainly broadened our knowledge of quadrature mice, and we used a few of them back in the day. If you only have a USB mouse and your computer expects one of these rarities, don’t worry, there’s an adapter for that.
2025-12-30 23:00:18
A friend of mine is producing a series of HOWTO videos for an open source project, and discovered that he needed a better microphone than the one built into his laptop. Upon searching, he was faced with a bewildering array of peripherals aimed at would-be podcasters, influencers, and content creators, many of which appeared to be well-packaged versions of very cheap genericised items such as you can find on AliExpress.
If an experienced electronic engineer finds himself baffled when buying a microphone, what chance does a less-informed member of the public have! It’s time to shed some light on the matter, and to move for the first time in this series from the playback into the recording half of the audio world. Let’s consider the microphone.
A microphone is simply a device for converting the pressure variations in the air created by sounds, into electrical impulses that can be recorded. They will always be accompanied by some kind of signal conditioning preamplifier, but in this instance we’re considering the physical microphone itself. There are a variety of different types of microphone in use, and after a short look at microphone history and a discussion of what makes a good microphone, we’ll consider a few of them in detail.
The development of the microphone in the late 19th century is intimately associated with that of the telephone rather than the phonograph, as these recording devices were mechanical only and had no electrical component. The first practical microphones for the telephone were carbon microphones, a container of carbon granules mechanically coupled to a metal diaphragm, which formed a crude variable resistor modified by the sound waves. They were especially suitable for the standing DC current of a telephone line and though they are too noisy for good quality audio they continued in use for telephones into recent decades. The ancestors of the microphones we use today would arrive in the early years of the 20th century along with the development of electronic amplification and recording.
The job of a microphone is to take the sounds surrounding it and convert them into electrical signals, and invariably that starts with some form of lightweight diaphragm which vibrates in response to the air around it. The idea is that the mass of the diaphragm is as low as possible such that its physical properties have a minimal effect on the quality of the audio it captures. This diaphragm will be surrounded by whatever supporting structure it needs as well as any other components such as magnets, and the structure surrounding it will be designed to minimise vibration and shape the polar pattern over which it is sensitive.
Depending on the application there are microphone designs with a variety of patterns, from an omnidirectional when recording a room, through bidirectional figure-of-eight used in some studio environments, to cardioid microphones for vocals and speech with a kidney-shaped pattern, to extremely directional microphones used by filmmakers. Of those the cardioid pattern is the one most likely to find itself in everyday use by someone like my friend recording voice-overs for video.
Having some idea of microphone history and principles, it’s time to look at some real microphones. We’re not going to cover every single type of microphone, instead we’re going to cover the three most common, to represent the ones you are likely to find for affordable prices. These are dynamic microphones, condenser microphones, and their electret cousins.
A dynamic microphone takes a coil of wire and suspends it from a diaphragm in a magnetic field. The diaphragm moves the coil, and thus an audio voltage is generated. The diaphragm will typically be a polymer such as Mylar, and it will usually be suspended around its edge by a folded section in a similar manner to what you may have seen on the edge of a loudspeaker cone. The output impedance depends upon the winding of the coil, but is typically in the range of a few hundred ohms. They have a low level output in the region of millivolts, and thus it is normal for them to connect to some kind of preamplifier which may be built in to a mixing desk or similar. The microphone cartridge pictured is from a cheap plastic bodied one bundled with a sound card. You can see the clear plastic diaphragm, as well as the coil. The magnet is the shiny metal object in the centre.
A capacitor microphone is, as its name suggests, a capacitor in which one plate is formed by a diaphragm.This diaphragm is usually an extremely thin polymer, metalised on one side.
The sound vibrations vary the capacitance of the device, and this can be retrieved as a voltage by maintaining a constant charge across the microphone. This is typically achieved with a DC voltage in the order of a few hundred volts. Since the charge remains constant while the capacitance changes with the sound, the voltage on the microphone will change at the audio frequency. Capacitor microphones have a high impedance, and will always have an accompanying preamplifier and power supply circuit as a result.
Electret microphones are a special class of capacitor microphone in which the charge comes from an electret material, one which holds a permanent electric charge. They thus forgo the high voltage power supply for their DC bias, and usually have a built-in FET preamp in the cartridge needing a low voltage supply such as a small battery. The attraction is that electret cartridges can be had for very little money indeed, and that the cheap electret cartridges are of surprisingly high quality for their price.
So yes, even knowing a bit about microphones, you’re still left just as confused when browsing the options. The questions you need to ask yourself aside from your budget then are these: what do I want to use if for, and what do I want to plug it in to? Let’s talk practicalities.
There are a variety of different physical form factors for microphones, usually at the cheaper end of the market a styling thing emulating famous more expensive models. Often the ones aimed at content creators have a built-in desk stand, however you may prefer the flexibility of your own stand. There are also all manner of pop filters and other accessories, some of which appear to be more for show than utility.
You will need to ask yourself what polar pattern you are looking for, and the answer is cardioid if you are recording your speech — its directional pattern rejects background noise, and focuses on what comes out of your mouth. You might also think about robustness; are you taking this microphone out on the road? A stage microphone makes a better choice if it will see a hard life, while a desktop microphone might make more sense if it rarely leaves your computer.
In front of me where this is being written is my microphone. I take it out on the road with me so I needed a robust device, plus I like the look of a traditional handheld microphone. The standard stage vocal dynamic microphones is unquestionably the Shure SM58, a robust and high-performance device that has stood the test of time. At £100, it’s out of my price range, so I have a cheaper mic from another well-known professional audio manufacturer that is obviously their take on the same formula. It is plugged in to a high-quality musician’s USB microphone interface, a USB sound card and mixer all-in-one. It serves me well, and if you’ve caught a Hackaday podcast with me on it you’ll have heard it in action.
If you’re not going to invest into an audio interface, you will be looking for something with a built-in amplifier and ADC, and probably something that plugs straight into USB. These are myriad, and the quality varies all over the place. For voice recording, a cardioid pattern makes sense, and an amplifier with low self-noise is desirable. If the amplifier picks up the USB bus noise, move on.
So in this piece I hope I’ve answered the questions of both my friend from earlier, and you the reader. It’s no primer for equipping a high-end studio, but if you’re doing that it’s likely you’ll already know a lot about microphones anyway.
2025-12-30 20:00:17
During the 1990s, everyone wanted to surf the information super-highway — also known as the World Wide Web or just ‘Internet’ — but not everyone was interested in getting one of those newfangled personal computers when they already had a perfect good television set. This opened a market for TV-connected thin clients that could browse the web with a much lower entry fee, with the WebTV service being launched in 1996. Bought by Microsoft in 1997 and renamed MSN TV, it lasted until 2013. Yet rather than this being the end, the service is now being revived by members of the community through the WebTV Redialed project.
The project, which was recently featured in a video by [MattKC], replaces the original back-end services that the thin clients connected to via their dial-up modems, with the first revision using a proprietary protocol. The later and much more powerful MSN TV 2 devices relied on a standard HTTP-based protocol running on Microsoft’s Internet Information Services (IIS) web server and Windows.
What’s interesting about this new project is that it allows you to not just reconnect your vintage WebTV/MSN TV box, but also use a Windows-based viewer and more. What difficulty level you pick depends on the chosen hardware and connection method. For example, you can pair the Raspberry Pi with a USB modem to get online thanks to the DeamPi project.
Interestingly, DreamPi was created to get the Sega Dreamcast back online, with said console also having its own WebTV port that can be revived this way. Just in case you really want to get the full Dreamcast experience.
2025-12-30 17:00:28
Bluetooth is everywhere, but it’s hard to inspect. Most of the magic is done inside a Bluetooth controller chip, accessed only through a controller-specific Host-Controller Interface (HCI) protocol, and almost everything your code does with Bluetooth passes through a binary library that speaks the right HCI dialect. Reverse engineering these libraries can get us a lot more control of and information about what’s going on over the radio link.
That’s [Anton]’s motivation and goal in this reversing and documentation project, which he describes for us in this great talk at this year’s Chaos Communication Congress. In the end, [Anton] gets enough transparency about the internal workings of the Bluetooth binaries to transmit and receive data. He stops short of writing his own BT stack, but suggests that it would be possible, but maybe more work than one person should undertake.
So what does this get us? Low-level control of the BT controller in a popular platform like the ESP32 that can do both classic and low-energy Bluetooth should help a lot with security research into Bluetooth in general. He figured out how to send arbitrary packets, for instance, which should allow someone to write a BT fuzzing tool. Unfortunately, there is a sequence ID that prevents his work from turning the controller into a fully promiscuous BT monitor, but still there’s a lot of new ground exposed here.
If any of this sounds interesting to you, you’ll find his write-up, register descriptions, and more in the GitHub repository. This isn’t a plug-and-play Bluetooth tool yet, but this is the kind of groundwork on a popular chip that we expect will enable future hacking, and we salute [Anton] for shining some light into one of the most ubiquitous and yet intransparent corners of everyday tech.
2025-12-30 14:00:49
Until the 2000s, game consoles existed primarily to bring a bit of the gaming arcade experience to homes, providing graphical feats that the average home computer would struggle to emulate. By the 2000s this changed, along with the idea of running desktop applications on gaming console for some reason. Hence we got Linux for the PlayStation 2, targeting its MIPS R5900 CPU and custom GPU. Unlike these days where game consoles are reskinned gaming PCs, this required some real effort, as well as a veritable stack of accessories, as demonstrated by [Action Retro] in a recent video.
Linux on the PlayStation 2 was a bit of a rare beast, as it required not only the optional HDD and a compatible ‘fat’ PS2, but also an Ethernet adapter, VGA adapter and a dedicated 8 MB memory card along with a keyboard and mouse. PS2 Linux users were also not free to do what they wanted, with e.g. ripping PS2 game discs disallowed, but you could make your own games. All of which had to fit within the PS2’s meagre 32 MB of RAM.
Of these accessories, the keyboard and mouse are standard USB – sadly not PS/2 – peripherals. The 40 GB HDD is a Sony-branded IDE HDD, while the Ethernet adapter is proprietary and also has the IDE HDD connector. This means that the VGA and Ethernet adapter are the two parts you absolutely need to source alongside a compatible PS2.
Linux is installed from the PS2 Linux DVD much like launching a game, with the memory card used for certain boot files. With it being based on Debian Linux, it should be quite familiar to most Linux users of the era, but there’s no fancy wizard to automagically do things like setting up the partitions. For this there is the paper manual to somewhat hold your hand.
After this you insert Disc 1 to boot from it and the memory card, ultimately finding yourself on the PS2 Linux desktop with Linux Kernel 2.2.1 for MIPS. As for what you can do with this in 2025, not too much. There’s still an active community with more up to date software that keeps the OS somewhat going, but in the end it’s still Linux running on a 32 MB MIPS system.
Despite only supporting PS2 Linux for a little while, the PlayStation 3 would also support installing other OSes like Linux and FreeBSD for a while alongside its native FreeBSD-based OS, but that got dropped as well along with the entire PS2 Emotion Engine chip for full PS2 backward compatibility and a host of other features. By the time the PlayStation 4 rolled around it seems that the idea of running a regular desktop OS on the hardware was no longer on Sony’s mind, making it a curious period in gaming console history.
2025-12-30 11:00:57
Scientific calculators are an amazing invention that take pocket calculators from being merely basic arithmetic machines to being pocket computers that can handle everything from statistics to algebra. That said, there are a few layers of scientific calculators, starting with those aimed at students. This is where Casio is very popular, especially because it uses traditional algebraic notation (VPAM) that follows the written style, rather than the reverse-polish notation (RPN) of HP and others. However, much like retro Casio wristwatches, it appears that these Casio calculators are now being (poorly) faked, as explained by [Another Roof] on YouTube.
The advanced fx-991 models are updated every few years, with the letters following the model indicating the year, such as fx-991EX standing for the 2015-released model. This was the model that got purchased online and which turned out to be fake. While the fx-991CW is newer, it changes the entire interface and is rightfully scolded in the video. Arguably this makes it the worst Casio scientific calculator in history.
After this run-down of how we got to the current Casio fx-991 model, we question why we don’t just use smartphones with a ‘scientific calculator’ app. The answers are ‘exams’ and ‘less complexity’, along with the tactile experience and how this enables muscle memory. Yet due to the CW model’s issues and disdain for muscle memory, the EX model is recommended by teachers. This then opens the market for knockoffs as Casio wanted everyone to move on to the CW model, and parents are always looking for that bargain deal with school supplies.
These fake EX models suffer from a variety of issues, depending on the internals. Some are noticeably slower, have omissions and even outright errors in their firmware that make them unusable for a variety of calculations. This makes it rough for both teachers and parents to find a good Casio scientific calculator, even as Casio has already reverted some of the controversial changes in the CW model in an admission of the problems they have caused.
Here’s hoping that Casio fully reverts to the EX-style of UI in its next 991-series calculator and finds a way to curb the spread of bad clones of its currently last good scientific calculator.
