How The IBM PC Went 8-Bit

May 17, 2022 by Al Williams 52 Comments

If you were around when the IBM PC rolled out, two things probably caught you by surprise. One is that the company that made the Selectric put that ridiculous keyboard on it. The other was that it had an 8-bit CPU onboard. It was actually even stranger than that. The PC sported an 8088 which was a 16-bit 8086 stripped down to an 8 bit external bus. You have to wonder what caused that, and [Steven Leibson] has a great post that explains what went down all those years ago.

Before the IBM PC, nearly all personal computers were 8-bit and had 16-bit address buses. Although 64K may have seemed enough for anyone, many realized that was going to be a brick wall fairly soon. So the answer was larger address buses and addressing modes.

Intel knew this and was working on the flagship iAPX 432. This was going to represent a radical departure from the 8080-series CPUs designed from the start for high-level languages like Ada. However, the radical design took longer than expected. The project started in 1976 but wouldn’t see the light of day until 1981. It was clear they needed something sooner, so the 8086 — a 16-bit processor clearly derived from the 8080 was born. Continue reading “How The IBM PC Went 8-Bit” →

Book Teaches Gaming Math

May 17, 2022 by Al Williams 13 Comments

If we knew how much math goes into writing a video game, we might have paid more attention in math class. If you need a refresher, [Fletcher Dunn] and [Ian Parbery] have their book “3D Math Primer for Graphics and Game Development” available free online. The book was originally a paper book from 2011 with a 2002 first edition but those are out of print now. However, math is math, so regardless of the age of the book, it is worth a look. For now, the online version is a bunch of web pages, but we hear a PDF or E-reader version is forthcoming.

There’s quite a bit of discussion about vectors, matrices, linear transformations, and 3D graphics. The last part of the book covers calculus, kinematics, and parametric curves. Some of these topics will be of interest even if you don’t care about graphics but do want to learn some math with practical examples.

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Falling Down The Labyrinth With Wooden Microphone Design

May 17, 2022 by Dan Maloney 7 Comments

It used to be that when we featured one of [Frank Olson]’s DIY ribbon microphone builds, it was natural to focus on the fact that he was building them almost exclusively from wood. But despite how counterintuitive it may seem, and for as many comments as we get that his microphones shouldn’t work without metal in the ribbon motors, microphones like this wooden RCA Model 77 reproduction both look and sound great.

But ironically, this homage features a critical piece that’s actually not made of wood. The 77’s pickup pattern was cardioid, making for a directional mic that picked up sound best from the front, thanks to an acoustic labyrinth that increased the path length for incoming sound waves. [Frank]’s labyrinth was made from epoxy resin poured into a mold made from heavy paper, creating a cylinder with multiple parallel tunnels. The tops and bottoms of adjacent tunnels were connected together, creating an acoustic path over a meter long. The ribbon motor, as close to a duplicate of the original as possible using wood, sits atop the labyrinth block’s output underneath a wood veneer shell that does its best to imitate the classic pill-shaped windscreen of the original. The video below, which of course was narrated using the mic, shows its construction in detail.

If you want to check out [Frank]’s other wooden microphones, and you should, check out the beautiful Model 44 replica that looks ready for [Sinatra], or the Bk-5-like mics he whipped up for drum kit recording.

Continue reading “Falling Down The Labyrinth With Wooden Microphone Design” →

Nanovolt Meter Requires Careful Design For Accuracy’s Sake

May 17, 2022 by Lewin Day 25 Comments

Measuring voltages is fairly straightforward most of the time. Simply grab any old cheap multimeter, hook up the probes, and read off the answer. If, however, you need to measure very tiny voltages, the problem gets more complex. [Jaromir-Sukuba] designed a nanovoltmeter specifically to deal with this difficult case.

The nanovoltmeter is exactly what it sounds like: a voltmeter that is sensitive and stable enough to measure and report voltages on the scale of nanovolts. Having a tool that can do this reliably can be very useful when it comes to measuring very small resistances or working with ever-so-slight differential voltages. Continue reading “Nanovolt Meter Requires Careful Design For Accuracy’s Sake” →

When Hams Helped Polar Researchers Come In From The Cold

May 17, 2022 by Al Williams 26 Comments

We always enjoy [The History Guy] videos, although many of them aren’t much about technology. However, when he does cover tech topics, he does it well and his recent video on how ham radio operators assisted in operation Deep Freeze is a great example. You can watch the video, below.

The backdrop is the International Geophysical Year (IGY) where many nations cooperated to learn more about the Earth. In particular, from 1957 to 1958 there was a push to learn more about the last unexplored corner of our planet: Antarctica. Several of the permanent bases on the icy continent today were started during the IGY.

It’s hard for modern audiences to appreciate what the state of personal communication was in 1957. There were no cell phones and if you are thinking about satellites, don’t forget that Sputnik didn’t launch until late 1957, so that wasn’t going to happen, either.

Operation Deep Freeze had ten U. S. Navy vessels that brought scientists, planes, and Seabees (slang for members of the Naval Construction Batallion) — about 1,800 people in all over several years culminating in the IGY. Of course, the Navy had radio capabilities, but it wasn’t like the Navy to let you just call home to chat. Not to mention, a little more than 100 people were left for each winter and the Navy ships went home. That’s where ham radio operators came in.

Hams would do what is called a phone patch for the people stationed in Antarctica. Some hams also send radiograms to and from the crew’s families. One teen named Jules was especially dedicated to making connections to Antarctica. We can’t verify it, but one commenter says that Jules was so instrumental in connecting his father in Antarctica to his fiancee that when his parents married, Jules was their best man.

Jules and his brother dedicated themselves to keeping a morale pipeline from New Jersey to the frozen stations. He figures prominently in recollections of many of the written accounts from people who wintered at the nascent bases. Apparently, many of the men even traveled to New Jersey later to visit Jules. What happened to him? Watch the end of the video and you’ll find out.

While being a ham today doesn’t offer this kind of excitement, hams still contribute to science. Want to get in on the action? [Dan Maloney] can tell you how to get started on the cheap.

Continue reading “When Hams Helped Polar Researchers Come In From The Cold” →

Kindle, EPUB, And Amazon’s Love Of Reinventing Wheels

May 17, 2022 by Tom Nardi 48 Comments

Last last month, a post from the relatively obscure Good e-Reader claimed that Amazon would finally allow the Kindle to read EPUB files. The story was picked up by all the major tech sites, and for a time, there was much rejoicing. After all, it was a feature that owners have been asking for since the Kindle was first released in 2007. But rather than supporting the open eBook format, Amazon had always insisted in coming up with their own proprietary formats to use on their readers. Accordingly, many users have turned to third party programs which can reliably convert their personal libraries over to whatever Amazon format their particular Kindle is most compatible with.

Native support for EPUB would make using the Kindle a lot less of a hassle for many folks, but alas, it was not to be. It wasn’t long before the original post was updated to clarify that Amazon had simply added support for EPUB to their Send to Kindle service. Granted this is still an improvement, as it represents a relatively low-effort way to get the open format files on your personal device; but in sending the files through the service they would be converted to Amazon’s KF8/AZW3 format, the result of which may not always be what you expected. At the same time the Send to Kindle documentation noted that support for AZW and MOBI files would be removed later on this year, as the older formats weren’t compatible with all the features of the latest Kindle models.

If you think this is a lot of unnecessary confusion just to get plain-text files to display on the world’s most popular ereader, you aren’t alone. Users shouldn’t have to wade through an alphabet soup of oddball file formats when there’s already an accepted industry standard in EPUB. But given that it’s the reality when using one of Amazon’s readers, this seems a good a time as any for a brief rundown of the different ebook formats, and a look at how we got into this mess in the first place.

Continue reading “Kindle, EPUB, And Amazon’s Love Of Reinventing Wheels” →

LED Backlight Brings Vibrant Colors To Classic Palm PDAs

May 17, 2022 by Robin Kearey 10 Comments

Back in the days before the widespread adoption of smartphones, Palm was the market leader in PDAs. If you had one of those you’ll probably remember taking notes by writing those funky “Graffiti” characters and tapping your stylus onto, usually, a green monochrome screen. Some models even came with a battery-hungry backlight, but for the ultimate display experience you had to buy the Palm IIIc that came with a backlit full-colour display.

While revolutionary for its time, it was hampered by the technology available: the CCFL backlight took a second to start up, and even with the screen at full brightness it was rather dim by today’s standards. [TobleMiner] fixed these issues by designing a module to retrofit an LED backlight into your Palm IIIc.

The new backlight consists of a long, thin PCB designed to fit exactly where the CCFL tube sits. The PCB holds twenty-one white LEDs along with their current-limiting resistors to provide even illumination from top to bottom. A little MOSFET soldered onto the mainboard ensures the new backlight also correctly responds to the device’s “brightness” setting. [TobleMiner] recommends to remove the bulky CCFL transformer from the Palm’s mainboard to disable the corresponding circuitry and save a bit of weight.

The end result is understandably hard to capture on camera, but apparently gives the screen more vibrant colours. In any case, this might be a useful hack for anyone with a Palm IIIc with a broken backlight, though we can’t remember if that was a common issue. If you’re among those who still use original Palm devices, you might like this Palm-compatible Bluetooth keyboard. Don’t have a classic PDA? You can also run PalmOS on modern custom hardware.