From PostScript To PDF

April 24, 2025 by Al Williams 34 Comments

There was a time when each and every printer and typesetter had its own quirky language. If you had a wordprocessor from a particular company, it worked with the printers from that company, and that was it. That was the situation in the 1970s when some engineers at Xerox Parc — a great place for innovation but a spotty track record for commercialization — realized there should be a better answer.

That answer would be Interpress, a language for controlling Xerox laser printers. Keep in mind that in 1980, a laser printer could run anywhere from $10,000 to $100,000 and was a serious investment. John Warnock and his boss, Chuck Geschke, tried for two years to commercialize Interpress. They failed.

So the two formed a company: Adobe. You’ve heard of them? They started out with the idea of making laser printers, but eventually realized it would be a better idea to sell technology into other people’s laser printers and that’s where we get PostScript.

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To See Within: Detecting X-Rays

April 23, 2025 by Dan Maloney 19 Comments

It’s amazing how quickly medical science made radiography one of its main diagnostic tools. Medicine had barely emerged from its Dark Age of bloodletting and the four humours when X-rays were discovered, and the realization that the internal structure of our bodies could cast shadows of this mysterious “X-Light” opened up diagnostic possibilities that went far beyond the educated guesswork and exploratory surgery doctors had relied on for centuries.

The problem is, X-rays are one of those things that you can’t see, feel, or smell, at least mostly; X-rays cause visible artifacts in some people’s eyes, and the pencil-thin beam of a CT scanner can create a distinct smell of ozone when it passes through the nasal cavity — ask me how I know. But to be diagnostically useful, the varying intensities created by X-rays passing through living tissue need to be translated into an image. We’ve already looked at how X-rays are produced, so now it’s time to take a look at how X-rays are detected and turned into medical miracles.

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Jenny’s (Not Quite) Daily Drivers: Raspberry Pi 1

April 14, 2025 by Jenny List 47 Comments

An occasional series of mine on these pages has been Daily Drivers, in which I try out operating systems from the point of view of using them for my everyday Hackaday work. It has mostly featured esoteric or lesser-used systems, some of which have been unexpected gems and others have been not quite ready for the big time.

Today I’m testing another system, but it’s not quite the same as the previous ones. Instead I’m looking at a piece of hardware, and I’m looking at it for use in my computing projects rather than as my desktop OS. You’ll all be familiar with it: the original Raspberry Pi appeared at the end of February 2012, though it would be May of that year before all but a lucky few received one. Since then it has become a global phenomenon and spawned a host of ever-faster successors, but what of that original board from 2012 here in 2025? If you have a working piece of hardware it makes sense to use it, so how does the original stack up? I have a project that needs a Linux machine, so I’m dusting off a Model B and going down memory lane.

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Ditto That

April 3, 2025 by Kristina Panos 42 Comments

In the 1982 movie Fast Times At Ridgemont High, a classroom of students receives a set of paperwork to pass backward. Nearly every student in the room takes a big whiff of their sheet before setting it down. If you know, you know, I guess, but if you don’t, keep reading.

Those often purple-inked papers were fresh from the ditto machine, or spirit duplicator. Legend has it that not only did they smell good when they were still wet, inhaling the volatile organic compounds within would make the sniffer just a little bit lightheaded. But the spirit duplicator didn’t use ghosts, it used either methanol (wood alcohol), isopropyl, or, if you were loaded, ethyl alcohol.

Invented in 1923 by Wilhelm Ritzerfeld, ditto machines were popular among schools, churches, and clubs for making copies of worksheets, fliers, and so on before the modern copy machine became widespread in the 1980s. Other early duplicating machines include the mimeograph, the hectograph, and the cyclostyle.

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On Egyptian Pyramids And Why It’s Definitely Aliens

April 1, 2025 by Maya Posch 63 Comments

History is rather dull and unexciting to most people, which naturally invites exciting flights of fancy that can range from the innocent to outright conspiracies. Nobody truly believes that the astounding finds and (fully functioning) ancient mechanisms in the Indiana Jones and Uncharted franchises are real, with mostly intact ancient cities waiting for intrepid explorers along with whatever mystical sources of power, wealth or influence formed the civilization’s foundations before its tragic demise. Yet somehow Plato’s fictive Atlantis has taken on a life of its own, along with many other ‘lost’ civilizations, whether real or imagined.

Of course, if these aforementioned movies and video games were realistic, they would center around a big archaeological dig and thrilling finds like pot shards and cuneiform clay tablets, not ways to smite enemies and gain immortality. Nor would it involve solving complex mechanical puzzles to gain access to the big secret chamber, prior to walking out of the readily accessible backdoor. Reality is boring like that, which is why there’s a major temptation to spruce things up. With the Egyptian pyramids as well as similar structures around the world speaking to the human imagination, this has led to centuries of half-baked ideas and outright conspiracies.

Most recently, a questionable 2022 paper hinting at structures underneath the Pyramid of Khafre in Egypt was used for a fresh boost to old ideas involving pyramid power stations, underground cities and other fanciful conspiracies. Although we can all agree that the ancient pyramids in Egypt are true marvels of engineering, are we really on the cusp of discovering that the ancient Egyptians were actually provided with Forerunner technology by extraterrestrials?

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AMSAT-OSCAR 7: The Ham Satellite That Refused To Die

March 29, 2025 by Maya Posch 46 Comments

When the AMSAT-OSCAR 7 (AO-7) amateur radio satellite was launched in 1974, its expected lifespan was about five years. The plucky little satellite made it to 1981 when a battery failure caused it to be written off as dead. Then, in 2002 it came back to life. The prevailing theory being that one of the cells in the satellites NiCd battery pack, in an extremely rare event, failed open — thus allowing the satellite to run (intermittently) off its solar panels.

In a recent video by [Ben] on the AE4JC Amateur Radio YouTube channel goes over the construction of AO-7, its operation, death and subsequent revival are covered, as well as a recent QSO (direct contact).

The battery is made up of multiple individual cells.

The solar panels covering this satellite provided a grand total of 14 watts at maximum illumination, which later dropped to 10 watts, making for a pretty small power budget. The entire satellite was assembled in a ‘clean room’ consisting of a sectioned off part of a basement, with components produced by enthusiasts associated with AMSAT around the world. Onboard are two radio transponders: Mode A at 2 meters and Mode B at 10 meters, as well as four beacons, three of which are active due to an international treaty affecting the 13 cm beacon.

Positioned in a geocentric LEO (1,447 – 1,465 km) orbit, it’s quite amazing that after 50 years it’s still mostly operational. Most of this is due to how the satellite smartly uses the Earth’s magnetic field for alignment with magnets as well as the impact of photons to maintain its spin. This passive control combined with the relatively high altitude should allow AO-7 to function pretty much indefinitely while the PV panels keep producing enough power. All because a NiCd battery failed in a very unusual way.

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Tech In Plain Sight: Hearing Aids

March 26, 2025 by Al Williams 38 Comments

You might think you don’t need a hearing aid, and you might be right. But in general, hearing loss eventually comes to all of us. In fact, you progressively lose hearing every year, which is why kids can have high-pitched ringtones their parents can’t hear.

You’d think hearing aids would be pretty simple, right? After all, we know how to pick up sounds, amplify them, and play them back. But there’s a lot more to it. Hearing aids need to be small, comfortable, have great battery life, and cram a microphone and speaker into a small area. That also can lead to problems with feedback, which can be very uncomfortable for the user. In addition, they need to handle very soft and loud sounds and accommodate devices like telephones.

Although early hearing aids just made sound louder and, possibly, blocked unwanted sound, modern devices will try to increase volume only in certain bands where the user has hearing loss. They may also employ sophisticated methods to block or reduce noise. Continue reading “Tech In Plain Sight: Hearing Aids” →