TV Typewriter Remembered

July 20, 2023 by Al Williams 23 Comments

With the recent passing of Don Lancaster, I took a minute to reflect on how far things have come in a pretty short period of time. If you somehow acquired a computer in the early 1970s, it was probably some discarded DEC, HP, or Data General machine. A few people built their own, but that was a stout project with no microprocessor chips readily available. When machines like the Mark-8 and, more famously, the Altair appeared, the number of people with a “home computer” swelled — relatively speaking — and it left a major problem: What kind of input/output device could you use?

An ad from Kilobaud offered you a ready-to-go, surely refurbished, ASR33 for $840

At work, you might have TeleType. Most of those were leased, and the price tag of a new one was somewhere around $1,000. Remember, too, that $1,000 in 1975 was a small fortune. Really lucky people had video terminals, but those were often well over $1,500, although Lear Siegler introduced one at the $1,000 price, and it became wildly successful. Snagging a used terminal was not very likely, and surplus TeleType equipment was likely of the 5-bit Baudot variety — not unusable, but not the terminal you really wanted.

A lot of the cost of a video terminal was the screen. Yet nearly everyone had a TV, and used TVs have always been fairly cheap, too. That’s where Don Lancaster came in. His TV Typewriter Cookbook was the bible for homebrew video displays. The design influenced the Apple 1 computer and spawned a successful kit for a company known as Southwest Technical Products. For around $300 or so, you could have a terminal that uses your TV for output. Continue reading “TV Typewriter Remembered” →

PCIe For Hackers: An M.2 Card Journey

July 20, 2023 by Arya Voronova 22 Comments

I’ve designed a few M.2 adapters for my own and my friends’ use, and having found those designs online, people have asked me for custom-made adapters. One of these requests is quite specific – an adapter that adds one more PCIe link to an E-key M.2 slot, the kind of slot you will see used in laptops for WiFi cards.

See, the M.2 specification allows two separate PCIe links connected to the E-key slot; however, no WiFi cards use this apart from some really old WiGig-capable ones, and manufacturers have long given up on connecting a second link. Nevertheless, there are some cards like the Google Coral M.2 E-key dual AI accelerator and the recently announced uSDR, that do indeed require the second link – otherwise, only half of their capacity is available.

It’s not clear why both Google and WaveletSDR designed for a dual-link E-key socket, since those are a rare occurrence; for the Google card, there are plenty of people complaining that the board they bought just doesn’t fully work. In theory, all you need to do to help such a situation, is getting a second PCIe link from somewhere, then wiring it up to the socket – and a perfect way to do it is to get a PCIe switch chip. You will lose out on some bandwidth because the uplink PCIe connection of the switch can only go so fast; for things like this AI accelerator, it’s not much of a problem since the main point is to get the second device accessible. For the aforementioned SDR, it might turn out useless, or you might win some but lose some – can’t know until you try! Continue reading “PCIe For Hackers: An M.2 Card Journey” →

Smart Assistants Need To Get Smarter

July 19, 2023 by Lewin Day 81 Comments

Science fiction has regularly portrayed smart computer assistants in a fanciful way. HAL from 2001: A Space Odyssey and J.A.R.V.I.S. from the contemporary Iron Man films are both great examples. They’re erudite, wise, and capable of doing just about any reasonable task that is asked of them, short of opening the pod bay doors.

Cut back to reality, and you’ll only be disappointed at how useless most voice assistants are. It’s been twelve long years since Siri burst onto the scene, with Alexa and Google Assistant following years later. Despite years on the market, their capabilities remain limited and uninspiring. It’s time for voice assistants to level up.

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Lighting Up With Chemistry, 1823-Style

July 19, 2023 by Dan Maloney 9 Comments

With our mass-produced butane lighters and matches made in the billions, fire is never more than a flick of the finger away these days. But starting a fire 200 years ago? That’s a different story.

One method we’d never heard of was Döbereiner’s lamp, an 1823 invention by German chemist Johann Wolfgang Döbereiner. At first glance, the device seems a little sketchy, what with a tank of sulfuric acid and a piece of zinc to create a stream of hydrogen gas ignited by a platinum catalyst. But as [Marb’s Lab] shows with the recreation in the video below, while it’s not exactly as pocket-friendly as a Zippo, the device actually has some inherent safety features.

[Marb]’s version is built mainly from laboratory glassware, with a beaker of dilute sulfuric acid — “Add acid to water, like you ought-er!” — bathing a chunk of zinc on a fixed support. An inverted glass funnel acts as a gas collector, which feeds the hydrogen gas to a nozzle through a pinch valve. The hydrogen gas never mixes with oxygen — that would be bad — and the production of gas stops once the gas displaces the sulfuric acid below the level of the zinc pellet. It’s a clever self-limiting feature that probably contributed to the commercial success of the invention back in the day.

To produce a flame, Döbereiner originally used a platinum sponge, which catalyzed the reaction between hydrogen and oxygen in the air; the heat produced by the reaction was enough to ignite the mixture and produce an open flame. [Marb] couldn’t come up with enough of the precious metal, so instead harvested the catalyst from a lighter fluid-fueled hand warmer. The catalyst wasn’t quite enough to generate an open flame, but it glowed pretty brightly, and would be more than enough to start a fire.

Hats off to [Marb] for the great lesson is chemical ingenuity and history. We’ve seen similar old-school catalytic lighters before, too.

Continue reading “Lighting Up With Chemistry, 1823-Style” →

Crab Shells Massively Improve Zinc-Ion Batteries

July 18, 2023 by Lewin Day 32 Comments

In the fast-moving world of battery research, scientists are constantly on the lookout for innovative materials with the right properties to help improve energy storage. Meanwhile, batteries are in greater demand than ever as production of EVs and renewable energy projects ramp up to new heights.

In the hunt for new and better battery materials, scientists found an unexpected hero: crab shells.Researchers at the University of Maryland have uncovered a remarkable breakthrough by exploring their use in battery production.

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DisplayPort: Under The Hood

July 17, 2023 by Arya Voronova 14 Comments

Last time, we looked at all the things that make DisplayPort unique for its users. What about the things that make it unique for hackers? Let’s get into all the ways that DisplayPort can serve you on your modern tech wrangling adventures.

You Are Watching The AUX Channel

With DisplayPort, the I2C bus we’ve always seen come bundled with VGA, DVI and HDMI, is no more – it’s been replaced by the AUX bus. AUX is a 1 MHz bidirectional diffpair – just a bit too complex for a cheap logic analyzer, though, possibly, something you could wrangle with the RP2040’s PIOs. Hacking thoughts aside, it’s a transparent replacement for I2C, so that software doesn’t have to be rewritten – for instance, it usually does I2C device passthrough over AUX, so that EDID data can still be stored in a separate EEPROM chip on the monitor or eDP LCD panel.

AUX isn’t just a differential bus, it’s more pseudodifferential, like USB2 – for instance, AUX_P and AUX_N are used separately, with a combination of 1 MΩ and 100 kΩ pullups and pulldowns signaling different states of the physical connection – for instance, a pullup on AUX+ and a pulldown on AUX- means that an external device has been connected. If you’d like to learn which combination of resistors means what, you can find in the DisplayPort specification, which isn’t distributed openly but isn’t hard to come by, either.

Also, DisplayPort link training happens over AUX, and in order to facilitate that, a piece of DisplayPort controller’s external memory is usually exposed over the AUX channel, through a mechanism that’s called DPCD. If you dig a bit, using “DPCD” as the keyword, you can easily reach into the lower-level details of your DisplayPort connection. Some of the DPCD memory map is static, and some parts are FIFOs you can funnel data into, or out of. You can find a wide variety of documents online which describe the DPCD structure – for now, here’s a piece of Bash that works on Linux graphics drivers for AMD and Intel, and will show you you the first 16 bytes of DPCD:

# sudo dd if=/dev/drm_dp_aux0 bs=1 skip=256 count=16 |xxd 00000000: 0084 0000 0000 0000 0108 0000 0000 0000 ................ [...]

In particular, the 4th nibble (digit) here describes the amount of lanes for the DisplayPort link established – as you can see, my laptop uses a four-lane link. Also, the /dev/drm_dp_aux0 path might need to be adjusted for your device. In case you ever want to debug your DP link, having direct access to the DPCD memory space like this might help you quite a bit! For now, let’s move onto other practical aspects. Continue reading “DisplayPort: Under The Hood” →

How Duck Tape Became Famous

July 13, 2023 by Al Williams 81 Comments

If you hack things in the real world, you probably have one or more rolls of duck tape. Outside of the cute brand name, many people think that duck tape is a malapropism, but in truth it is the type of cloth traditionally used in our favorite tape: cotton duck. However, as we’ll see, it’s not entirely wrong to call it duct tape either. Whatever you call it, a cloth material has an adhesive backing and is coated with something like polyethylene.

Actually, the original duck tape wasn’t adhesive at all. It was simply strips of cotton duck used for several purposes, including making shoes and wrapping steel cables like the ones placed in 1902 at the Manhattan Bridge. By 1910, the tape was made with adhesive on one side and soaked in rubber, found use in hospitals for binding wounds. In May 1930, Popular Mechanics advised melting rubber from an old tire and adding rosin to create a compound to coat cotton tape, among other things.

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