Author: Maya Posch

1502 Articles

Dreamcast Linux: Looking Back At Linux On A SuperH-based Gaming Console

March 20, 2023 by 12 Comments

The Dreamcast is probably best known as the swansong of Sega’s ambitions as a gaming console manufacturer, but perhaps lesser known is the fact that you can run Linux on it. In a deep-dive by [Cameron Kaiser] over at the Old VCR blog, it is demonstrated what it takes to make this feat even work in 2023, and what one can expect from a system with a 200 MHz HItachi SuperH SH-4 CPU, 16 MB of RAM and the luxuries of VGA and network interfaces.

What’s interesting about Dreamcast Linux is that it was among the first times that Linux got put on a gaming console, even if it wasn’t entirely official or remotely supported by Sega. In fact, the fact that it works at all has its roots firmly in an exploit that was discovered shortly after the Dreamcast’s release. While Dreamcast discs are generally in a format called GD-ROM (Gigabyte Disc), early on it also supported the MIL-CD standard, which was Sega’s ill-fated attempt at creating multimedia CDs with MIL-CDs.

Not only did MIL-CDs flop in the market, the support form in Dreamcast units also provided a juicy exploit via the firmware that handles detecting and switching between GD-ROM and the much more constrained, audio-only MIL-CD mode. Later Dreamcast models dropped MIL-CD support and will thus also not boot Dreamcast Linux, which is an important gotcha to keep in mind when dragging out a Dreamcast for some Linux action.

As for running Linux on a Dreamcast, it’s pretty much what you’d expect from running it on such a constrained, RAM-disk only device. While [Cameron] was able to use workarounds such as swap-over-NFS to increase functionality, a lot more work remains to be done. Linux SuperH support seems to have petered out around the 2.6.x era, which would seem to have cemented the fate of Dreamcast Linux and similar SuperH platforms.

We’re curious, would double the RAM make a difference to this Linux platform?

Another Room-Temperature Superconductivity Claim And Questions Of Scientific Integrity

March 20, 2023 by 46 Comments

In early March of 2023, a paper was published in Nature, with the researchers claiming that they had observed superconductivity at room temperature in a conductive alloy, at near-ambient pressure. While normally this would be cause for excitement, what mars this occasion is that this is not the first time that such claims have been made by these same researchers. Last year their previous paper in Nature on the topic was retracted after numerous issues were raised by other researchers regarding their data and the interpretation of this that led them to conclude that they had observed superconductivity.

According to an interview with one of the lead authors at the University of Rochester – Ranga Dias – the retracted paper has since been revised to incorporate the received feedback, with the research team purportedly having invited colleagues to vet their data and experimental setup. Of note, the newly released paper reports improvements over the previous results by requiring even lower pressures.

Depending on one’s perspective, this may either seem incredibly suspicious, or merely a sign that the scientific peer review system is working as it should. For the lay person this does however make it rather hard to answer the simple question of whether room-temperature superconductors are right around the corner. What does this effectively mean?

Continue reading “Another Room-Temperature Superconductivity Claim And Questions Of Scientific Integrity” →

A Look At Zweikanalton Stereo Audio And Comparison With NICAM

March 19, 2023 by 1 Comment

With how we take stereo sound for granted, there was a very long period where broadcast audio and television with accompanying audio track were in mono. Over the decades, multiple standards were developed that provide a way to transmit and receive two mono tracks, as a proper stereo transmission. In a recent video, [Matt] over at [Matt’s Tech Barn] takes a look at the German Zweikanalton (also known as A2 Stereo) standard, and compares it with the NICAM standard that was used elsewhere in the world.

Zweikanalton is quite simple compared to NICAM (which we covered previously), being purely analog with a second channel transmitted alongside the first. Since it didn’t really make much of a splash outside of the German-speaking countries, equipment for it is more limited. In this video [Matt] looks at the Philips PM 5588 and Rohde & Schwarz 392, analyzing the different modulations for FM, Zweikanalton and NICAM transmissions and the basic operation of the modulator and demodulator equipment.

An interesting aspect of these modulations are the visible sidebands, and the detection of which modulation is used. Ultimately NICAM’s only disadvantage compared to Zweikanalton was the higher cost of the hardware, but with increased technological development single-chip NICAM solutions like the Philips SAA7283 (1995) began to reduce total system cost and by the early 2000s NICAM was a standard feature of TV chipsets, just in time for analog broadcast television to essentially become irrelevant.

Continue reading “A Look At Zweikanalton Stereo Audio And Comparison With NICAM” →

The Intricacies Of Starting A Rocket Engine

March 19, 2023 by 11 Comments

Rockets are conceptually rather simple: you put the pointy bit upwards and make sure that the bit that will go flamey points downwards before starting the engine(s). Yet how to start each rocket engine type in a way that’s both safe and effective? Unlike in the Wile E. Coyote cartoons, real-life rocket engines do not have a fuse you light up before dashing off to a safe distance. Rather they use increasingly more complicated methods, which depend on the engine type and fuels used. In a recent article written by [Trevor Sesnic] with accompanying video featuring everyone’s favorite Everyday Astronaut [Tim Dodd], we’re taken through the intricacies of how flamey ends are made. Continue reading “The Intricacies Of Starting A Rocket Engine” →

Customizing The Start-Up Chime On A 1999 G3 IMac

March 19, 2023 by 3 Comments

The start-up chime on Macs is probably as recognizable as the default Nokia ringtone in this day and age. Yet much like a ringtone, so too one might want to change the start-up chime on a Mac. This is something which [Doug Brown] has done in the past already on a Power Mac G3 in 2012, which made him instantly an expert on the topic in the eyes of a reader who wanted to know how to change the chime on a 1999 iMac. While the firmware on both these systems is written in Forth, it did take a bit of sleuthing to figure out where the chime was hiding in the firmware image, and how to change it.

The target iMac is somewhat unique in that it has a G4 PPC CPU rather than the more common G3. The firmware is similar enough that it was a snap to simply search the newer iMac’s firmware for the signature of the chime sound data. This turned out to be the identical QuickTime IMA ADPCM format-encoded data, yet what was different was how this data was integrated into the firmware image. Key is finding the area in the firmware where not only the address of the chime data’s start is defined, but also its length. Finally, the checksums in the firmware image have to be updated so that it matches the patched data.

Reverse-engineering the checksum calculation in the Forth code turned out to be fairly straightforward, but getting the new firmware on the iMac turned out to be the biggest struggle, as [Doug] didn’t want to inflict running a manual firmware update onto this reader he was doing all this work for. This led [Doug] to do some more reverse-engineering using Ghidra to enable the use of the automatic updater like a regular firmware update.

In the end it all worked out great, and now another iMac no longer has the Mac chime on start-up.

Building A Truss-Braced Model Airplane: Sense Or Nonsense?

March 18, 2023 by 13 Comments

Following NASA’s recent results with truss-braced wing airplanes and the benefits this could bring to full-sized airplanes, [Think Flight] figured that if it helps with those airplanes, perhaps it may also be a boon for model airplanes. With the recent construction of a carrier airplane for smaller drones, he decided to give the concept a whirl to see whether it would make a difference compared to a regular wing design. This carrier airplane features a payload bay that can be opened in flight to release the drones stored inside it, making any potential increased payload capacity and improvements to the flight characteristics very welcome.

Continue reading “Building A Truss-Braced Model Airplane: Sense Or Nonsense?” →

Efficient X86_64 Emulation With Box86

March 12, 2023 by 5 Comments

Running applications on a different architecture than the one for which they were compiled is a common occurrence, not in the least with Apple’s architectural migration every decade or so. It’s also commonly used with for example ARM, OpenRISC, and RISC-V systems to run applications that are only available for x86 or x86_64. While QEMU and kin are often used here, they’re pretty resource heavy, which is where an option like Box86 and its 64-bit sibling Box64 are attractive options. Unlike QEMU, both offer dynamic recompilation and redirection of dynamic library calls to native libraries, including those for SDL and OpenGL.

Both are available on GitHub under an MIT license, with Box64 probably the most interesting these days as applications and games have moved on to a 64-bit only world. The only hard requirement that Box64 has for a host system is that it is little-endian, which is a pretty easy requirement to meet. The most recent release was on March 10th, with Box86 0.3 and Box64 0.2.2. As essentially a translation layer, it does not offer full compatibility with every bit of software out there, but it’s already good enough to run Steam, GoG, and Epic Game Store clients and install and run Windows games via Wine for x86.

A simple set of benchmarks comparing it with QEMU and FEX (another emulator) shows it to run both more applications, and with significantly better performance.