FM Radio Is Discriminating

AM radios were easy to understand. The strength of the signal goes up and down, and the audio follows. FM radio is a little more difficult. [AllAmericanFiveRadio] has an old tube FM set and takes us on a tour of how the FM discriminator works. You can see the video below.

The first step is to look at the IF signal on the scope. It is hard to see, but the frequency is changing, and that’s the basis of modulation that the discriminator has to resolve.

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640k Was Never Enough For Anyone: How DOS Broke Free

On modern desktop and laptop computers, there is rarely a need to think about memory. We all have many gigabytes of the stuff, and it’s just there. Our operating system does the heavy lifting of working out what goes where and what needs to be paged to disk, and we just get on with reading Hackaday, that noblest of computing pursuits. This was not always the case though, and for early PCs in particular the limitations of the 8086 processor gave the need for some significant gymnastics in search of an extra few kilobytes. [Julio Merion] has an interesting run-down of the DOS memory map, and how memory expansion happened on computers physically unable to see much of it.

The 8086 has a 20-bit address bus, giving it access to a maximum of 1 megabyte. When IBM made the PC they needed space for the BIOS, the display, and the various accessory ROMs intended to come with expansion cards. Thus they allocated a maximum 640k of the map for RAM, and many early machines shipped with much less than that. The quote from Bill Gates about 640k being enough for anyone is probably apocryphal, but it was pretty clear as the 1980s wore on that more would be needed. The post goes into how memory expansion worked, with a 64k page mapped to switchable RAM on a card, and touches on how DOS managed extended memory above 1 Mb on the later processors that supported it. We dimly remember there also being a device driver that would map the unused graphics memory as EMS when the graphics card was running in text mode, but such horrors are best left behind.

Of course, some of the tricks to boost RAM were nothing but snake oil.

8086 header: Thomas Nguyen, CC BY-SA 4.0

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Hackaday Links: January 21, 2024

Have you noticed any apps missing from your Android phone lately? We haven’t but then again, we try to keep the number of apps on our phone to a minimum, just because it seems like the prudent thing to do. But apparently, Google is summarily removing apps from the Play Store, often taking the extra step of silently removing the apps from phones. The article, which seems to focus mainly on games, and has a particular bone to pick about the removal of RPG Wayward Souls, isn’t clear about how widespread the deletions are, or what exactly the reason behind the removals could be. But they sure are exercised about it, and rightly so since in some cases the deleted games have actually been paid for by the users, and Google pretty much says that if you think you’re getting a refund, think again. They make some interesting points, such as this being the very definition of larceny, while also acknowledging that in all likelihood Google has a get-out-of-jail-free card buried in some EULA somewhere permitting them to do exactly what they’re doing. Google’s gonna Google, right?

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Simulating Cellular Biology In The Browser

[Technistuff] read a paper about simulating a “minimal” cell — apparently a cell with only 493 genes. This led to a goal: reproduce the simulation in TypeScript so it can run in a web browser. Why? We don’t know, but it is an interesting look at both in-depth biology and how to handle complex simulations. The code is available on GitHub.

For a point of reference, E. Coli has over 4,500 genes. The cell in question — JCVI-syn3A — actually has seven more genes than truly necessary. The data for this bacteria is available from a research lab, again, using GitHub.

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Creators Can Fight Back Against AI With Nightshade

If an artist were to make use of a piece of intellectual property owned by a large tech company, they risk facing legal action. Yet many creators are unhappy that those same tech companies are using their IP on a grand scale in the form of training material for generative AI. Can they fight back?

Perhaps now they can, with Nightshade, from a team at the University of Chicago. It’s a piece of software for Windows and MacOS that poisons an image with imperceptible shading, to make an AI classify it in an entirely different way than it appears.

The idea is that creators use it on their artwork, and leave it for unsuspecting AIs to assimilate. Their example is that a picture of a cow might be poisoned such that the AI sees it as a handbag, and if enough creators use the software the AI is forever poisoned to return a picture of a handbag when asked for one of a cow. If enough of these poisoned images are put online then the risks of an AI using an online image become too high, and the hope is that then AI companies would be forced to take the IP of their source material seriously.

For this to work it depends on enough creators taking up and using the software, but we are guessing that an inevitable result will be an arms race between AIs and image poisoners. One thing is certain though, as the AI hype has fueled such a growth in generative AI systems, creators, whether they be major publishers, your favourite human-generated tech news website, or someone drawing a cartoon strip in their bedroom, deserve not to have their work stolen in this way.

Computer Logic Spins With No Electricity

We’ve often said you can make a logic gate out of darn near anything. [The Action Lab] agrees and just released a video showing how he made some logic gates from chains and gears. Along the way, he makes the case that the moving chain is an analog for electric current. The demonstration uses a commercial toy known as Spintronics, but if you are mechanically handy, you could probably devise your own setup using 3D printing or gears.

A spring wound motor is a “battery.” Gears act like resistors and junctions to distribute “current” in multiple directions. Seeing series and parallel resistance as moving chains is pretty entertaining and might help someone new learn those concepts.

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Reverse-Engineering The Web-@nywhere Watch For 2001-Era Smartwatch Action

Although smartwatches seem to be just a recent fad, people have been strapping wristwatches to their wrists with all kinds of functionality. Whether a miniscule calculator, a remote control, an organizer or as in the case of the Web-@nywhere Watch a web browser. In the last case only sort of, naturally, as it was released in 2001 and this little early 2000s marvel cost only $85 (or $150 in 2024 USD), so what could it really be capable of? This is the million dollar question that [Cameron Kaiser] sought to find out as he found a new-in-box unit for sale.

The Web-@nywhere watch in action. (Credit: Cameron Kaiser)
The Web-@nywhere watch in action. (Credit: Cameron Kaiser)

Beforehand he knew already that the unit required interaction with a PC-based application to sync the 93 kB of on-watch data, with the required software and remote servers now being very much outdated and/or gone. This required some reverse-engineering to once more bring this watch widget back to life. Along the way it became also quite clear that this watch was designed as a cheap rip-off of the much better 1998 Seiko Ruputer – which later got sold also as the onHand PC – using the same joystick-driven interface.

After some poking around with the Windows-based software that came with the watch [Cameron] quickly realized that while it could establish a serial link with the watch in its cradle, it fully relied on a now defunct FTP server formerly run by the manufacturer, Kinger, along with any games and content on it. Since FTP servers were never archived like HTTP sites, this content is likely gone forever.

Fortunately, the protocol between the PC and the watch is a standard serial link (with parity), so [Cameron] was able to sniff the serial traffic and figure out the protocol, the results of which he has made available on GitHub in the form of a Perl script for transforming text and a C-based application to do the uploading. Now once again Web-@nywhere users can proudly roam the streets with 2024-era website content on their wrists.