An Optical Computer Architecture

March 12, 2024 by 13 Comments

We always hear that future computers will use optical technology. But what will that look like for a general-purpose computer? German researchers explain it in a recent scientific paper. Although the DOC-II used optical processing, it did use some conventional electronics. The question is, how can you construct a general computer that uses only optical technology?

The paper outlines “Miller’s criteria” for practical optical logic gates. In particular, any optical scheme must provide outputs suitable for introduction to another gate’s inputs and also support fan out of one output to multiple inputs. It is also desirable that each stage does not propagate signal degradation and isolate its outputs from its inputs. The final two criteria note that practical systems don’t depend on loss for information representation since this isn’t reliable across paths, and, similarly, the gates should require high-precision adjustment to work correctly.

The paper also identifies many misconceptions about new computing devices. For example, they assert that while general-purpose desktop-class CPUs today contain billions of devices, use a minimum of 32-bits of data path, and contain RAM, this isn’t necessarily true for CPUs that use different technology. If that seems hard to believe, they make their case throughout the paper. We can’t remember the last scientific paper we read that literally posed the question, “Will it run Doom?” But this paper does actually propose this as a canonical question.

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Pictures of the internals of the Starlink adapter

Restoring Starlink’s Missing Ethernet Ports

February 28, 2024 by 29 Comments

Internet connectivity in remote areas can be a challenge, but recently SpaceX’s Starlink has emerged as a viable solution for many spots on the globe — including the Ukrainian frontlines. Unfortunately, in 2021 Starlink released a new version of their hardware, cost-optimized to the point of losing some nice features such as the built-in Ethernet RJ45 (8P8C) port, and their proposed workaround has some fundamental problems to it. [Oleg Kutkov], known for fixing Starlink terminals in wartime conditions, has released three posts on investigating those problems and, in the end, bringing the RJ45 ports back.

Starlink now uses an SPX connector with a proprietary pinout that carries two Ethernet connections at once: one to the Dishy uplink, and another one for LAN, with only the Dishy uplink being used by default. If you want LAN Ethernet connectivity, they’d like you to buy an adapter that plugs in the middle of the Dishy-router connection. Not only is the adapter requirement a bother, especially in a country where shipping is impeded, the SPX connector is also seriously fragile and prone to a few disastrous failure modes, from moisture sensitivity to straight up bad factory soldering.

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Apple Pushes Back On Right To Repair Bill Due To Parts Pairing

February 14, 2024 by 64 Comments

After previously supporting one in California, Apple has made an about-face and is now pushing back against a “Right to Repair” bill (Senate Bill 1596) currently under consideration in Oregon. The reason for this appears to be due to this new bill making parts pairing illegal, as reported by [404media] and [PCMag].

The practice of parts pairing is becoming ever more prevalent with Apple devices, which links specific parts of a system such as cameras, displays, batteries, and fingerprint sensors to the mainboard. During the open hearing on the newly proposed Oregonian bill, Apple’s [John Perry] insisted that this parts pairing is done for user security, safety and privacy.

Even in we take that claim at face value, the fact remains that with parts pairing in place, only authorized Apple repair centers can routinely replace components — while user repairs are limited to specific devices with limited part availability. Even in the latter case the user still has to contact Apple to have them reauthorize the replaced part. This is becoming an issue with Apple’s MacBooks as well, where the lid angle sensor requires calibration using a proprietary tool.

During the same hearing, the director of an Oregon nonprofit organization noted that of the 15,000 iPhones which they had donated to them last year, only 300 could be refurbished due to parts pairing. The remainder of otherwise perfectly fine phones are discarded for recycling, which is terrible for everyone but Apple. Whether the parts pairing element of the bill survives it to the final form remains to be seen, but if it passes it’d set the trend for future bills in other states as well as amendments to existing ones.

Thanks to [paulvdh] for the tip.

Piezo Transducers Could Turn Displays Into Speakers

February 13, 2024 by 28 Comments

Will piezoelectric-based speakers replace traditional speakers over the coming years in space-constrained devices? We have definitely seen the use of piezo transducers in e.g. high-end televisions that use the display’s surface not just for the visual content, but also as a highly dynamic speaker. If you extrapolate this principle to something like smartphones, tablets and laptops the advantages are clear: piezoelectric transducers are smaller, more power efficient and do not need any holes in the enclosure. These and other advantages are what [Vineet Ganju] argues in IEEE Spectrum will push the market to adopt this new technology.

When piezoelectric transducers vibrate the display itself to create sound waves, the sound seems to come directly from the image on the screen, a much more realistic effect. (Credit: James Provost)
Piezoelectric transducers vibrate the display itself to create sound waves. (Credit: James Provost)

[Vineet] is the Vice President and General Manager of the audio business unit of Synaptics — which is one of the companies pushing for these piezoelectric transducers to be used for speaker purposes — so there is definitely some bias involved. Even so, it’s undeniable that the speakers in portable devices as well as the average flat panel TV aren’t exactly amazing, with the limited space meaning that audio quality suffers, with lows being generally absent and the resulting audio sounding ‘tinny’. Generally this is where people get external speakers for their TV, and lug portable speakers along with their laptop and other mobile devices.

For TVs, Sony has pushed for its Acoustic Surface Audio technology that uses two or three piezoelectric transducers on their OLED panels, while Samsung sticks to traditional speakers, but places lots of them around the screen with its Object Tracking Sound technology.

Sony’s technology cannot be used with LCD panels, due to the backlight being in the way, so the interesting question here is whether the piezoelectric speaker revolution proposed by [Vineet] will be limited to devices that use OLED or similar backlight-less displays?

The Gyro Monorail: How To Make Trains Better With A Gyroscope

January 31, 2024 by 10 Comments
The gyroscopic system for gyro monorail trains that Brennan developed. (Credit: Primal Space)

Everyone who has ever handled a spinning gyroscope found themselves likely mesmerized by the way it absolutely maintains its orientation even when disturbed. Much of modern technology would be impossible without them, whether space telescopes or avionics. Yet during the early 20th century a much more radical idea was proposed for gyroscopes, one that would essentially have turned entire trains into gyroscopes. This was the concept of the Gyro Monorail, with Louis Brennan being among those who built a full-sized, working prototype in 1910, with its history and fate covered in detail by [Primal Space], along with an accompanying video.

At first glance it may seem rather daft to have an entire train balancing on a single rail track, using nothing but gyroscopic forces to keep the entire contraption level and balanced even when you feel the thing should just tip over. Yet the gyroscopic system that Brennan created and patented in 1903 turned out to function really well, and reliably kept the train on its single track. Key to this was the use of two gyroscopic wheels, each spinning in an opposite direction, with a pneumatic system linked to a gear system between the two wheels that used the gyroscope’s precession in corners to quickly establish a new balance.

Despite this success, investors were unconvinced, and regular trains were already firmly established, and the system would also require that each car had its own gyro system. Even so, the idea of the gyro monorail never truly died, as evidenced by the recently created German MonoCab-OWL project. This targets converting single-rail sections into dual-rail, bi-directional service with no infrastructure investment required.

Thanks to [Stephen Walters] for the tip.

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The Past, Present, And Future Of Inflatable Space Habitats

January 30, 2024 by 23 Comments

Recently, a prototype inflatable space station module built by Sierra Space exploded violently on a test stand at NASA’s Marshall Space Flight Center in Alabama. Under normal circumstances, this would be a bad thing. But in this case, Sierra was looking forward to blowing up their handiwork. In fact, there was some disappointment when it failed to explode during a previous test run.

LIFE Module Burst Test

That’s because the team at Sierra was looking to find the ultimate bust pressure of their 8.2 meter (26.9 foot) diameter Large Integrated Flexible Environment (LIFE) module — a real-world demonstration of just how much air could be pumped into the expanding structure before it buckled. NASA recommended they shoot for just under 61 PSI, which would be four times the expected operational pressure for a crewed habitat module.

By the time the full-scale LIFE prototype ripped itself apart, it had an internal pressure of 77 PSI. The results so far seem extremely promising, but Sierra will need to repeat the test at least two more times to be sure their materials and construction techniques can withstand the rigors of spaceflight.

Sierra is a targeting no earlier than 2026 for an in-space test, but even if they nail the date (always a dubious prospect for cutting edge aerospace projects), they’ll still be about 20 years late to the party. Despite how futuristic the idea of inflatable space stations may seem, NASA first started experimenting with the concept of expandable habitat modules back in the 1990s, and there were practical examples being launched into orbit by the early 2000s.

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Displays We Love Hacking: Parallel RGB

January 25, 2024 by 8 Comments

You might have seen old display panels, from 3″ to 10″, with 40-pin FFC connectors where every pin seems to be used for some data signal. We call these displays parallel RGB, or TTL RGB, or DPI, and you can find them in higher-power MCU, Raspberry Pi, and other Linux SBC projects. You deserve to know what to do with those – let’s take a look.

The idea is simple – this interface requires you to constantly send a stream of pixels to the display, and you need to send those pixels through a parallel bus. You can send up to 8 bits per color channel per pixel, which makes for 24 bits, and the 24-bit mode is indeed the standard, but in practice, many parallel RGB implementations don’t bother with more than 5-6 bits of color – two common kinds of parallel RGB links are RGB565 and RGB666. The parallel RGB interface is a very straightforward approach to sending pixels to your display, and in many cases, you can also convert parallel RGB to LVDS or VGA interfaces relatively easily!

If you’re new to it, the easiest way you can drive a parallel RGB display is from a Raspberry Pi, where the parallel RGB interface is known as DPI. This is how 800 x 480 display Pi HATs like the Pimoroni HyperPixel work – they use up almost all of the GPIOs on your Pi, but you get a reasonably high-resolution display with a low power footprint, and you don’t need any intermediate ICs either. FPGAs and some higher-grade MCUs also often have parallel RGB output capability, and surely, someone could even use the RP2040 PIO as well!

Throughout the last decade, parallel RGB has been used less and less, but you will still encounter it – maybe you’re working with an old game console like the PSP and would like to put new guts into it, maybe you’re playing with some tasty display that uses parallel RGB, or maybe you’d like to convert parallel RGB into something else while treating it with respect! Let’s go through what makes parallel RGB tick, what tools you have got to work with it, and a few tips and tricks. Continue reading “Displays We Love Hacking: Parallel RGB” →