Author: Al Williams

3960 Articles

Mechanical Calculator Finds Derivatives

January 6, 2025 by 10 Comments

We like mechanical calculators like slide rules, but we have to admit that we had not heard of the Ott Derivimeter that [Chris Staecker] shows us in a recent video. As the name implies, the derivimeter finds the derivative of a function. To do that, you have to plot the function on a piece of paper that the meter can measure.

If you forgot calculus or skipped it altogether, the derivative is the rate of change. If you plot, say, your car’s speed vs time, the parts where you accelerate or decelerate will have a larger derivative (either positive or negative, in the decelerate case). If you hold a steady speed, the derivative will be zero.

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Perfecting 20 Minute PCBs With Laser

January 5, 2025 by 40 Comments

Normally, you have a choice with PCB prototypes: fast or cheap. [Stephen Hawes] has been trying fiber lasers to create PCBs. He’s learned a lot which he shares in the video below. Very good-looking singled-sided boards take just a few minutes. Fiber lasers are not cheap but they are within range for well-off hackers and certainly possible for a well-funded hackerspace.

One thing that’s important is to use FR1 phenolic substrate instead of the more common FR4. FR4 uses epoxy which will probably produce some toxic fumes under the laser.

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Stacy’s Computer Has Got It Going On

January 5, 2025 by 14 Comments

According to [ClassicHasClass], the best way to open an Atari Stacy is to not open an Atari Stacy. Apparently, these old computers were not pleasant to work on. The cables were not keyed and were prone to short against things. Screws easily strip out plastic holes. Of course, there wouldn’t be a story if there wasn’t a teardown and an upgrade that you can check out in the post.

The Stacy was one of Atari’s earliest portable systems and the first ST portable (that is, STacy). There’s a backlit LCD, a keyboard and trackball, and the usual ports. You could make do with a single floppy or spring for a second floppy or an internal SCSI hard drive. The 8 MHz 68000-based machine would set you back north of $2,300 back in 1989.

The original plan was to run the thing on C-cell batteries, but that would give you about 15 minutes of operation. They finally decided it was a luggable — you’d have to plug it into the wall. The battery compartment was there, but empty and glued shut.

Apparently, there were about 35,000 of these made, but they seem somewhat rare. But we do like a rare retrocomputer. Or even some that aren’t so rare.

16-bit Linux-like Goodness

January 5, 2025 by 15 Comments

We see many 16-bit retrocomputers around here based on Intel and Intel-like chips such as the 8086, 8088, V20, and similar. While they don’t seem very powerful by today’s standards, they were perfectly capable machines and, thanks to Elks (Embeddedable Linux Kernel Subset), you can run something fairly Linux-like on these devices.

The requirements are light: 512K of RAM is desirable, but you can do something with 256K. If you have ROM, you can even get by with 128K. Most importantly, the system doesn’t require a memory management unit to remap memory like many operating systems.

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Self Driving Like It’s 1993

January 4, 2025 by 20 Comments

In a stunning example of the Baader Meinhof effect, we’ve recently heard several times this week about events like the “carbage run.” That is, a motoring event where you can only buy some garbage car to compete. In the case of [Robbe Derks], the idea was to take a six-day journey to the polar circle in a car. But not just any car. It had to be at least 20 years old and cost less than €1000. That wasn’t hard enough for [Robbe] and friends. They also decided to make the car self-driving.

If you have a car that is new enough, this might not be as hard as it sounds. The OpenPilot project adds L2 self-driving features to about 275 car models. But probably not a 20-year-old junker or, in particular, a 1993 Volvo 940. [Robbe] took up the challenge and is doing a series of blog posts covering how it all worked.

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High Performance RISC-V

January 3, 2025 by 9 Comments

From the Institute of Computing Technology division of the Chinese Academy of Sciences and Peng Cheng Laboratory comes a high-performance and well-documented RISC-V core called XiangShan.

In the Git repository, you’ll find several branches including at least two stable branches: Yanqihu and Nanhu. The currently developed architecture, Kunminghu, is impressive, with a sophisticated instruction fetch unit, a reorder buffer, and a register renaming scheme.

The point of these types of circuits in a CPU is to allow multiple instructions to process at once. This also implies that instructions can be executed out of order. A cursory glance didn’t show any branch prediction logic, but that may be a limitation of the documentation. If there isn’t one, that would be an interesting thing to add in a fork if you are looking for a project.

On the computing side, the processor contains an integer block, a floating point unit, and a vector processor. Clearly, this isn’t a toy processor and has the capability to compete with serious modern CPUs.

There is a separate GitHub for documentation. It looks like they try to keep documentation in both Mandarin and English. You can also find some of the academic papers about the architecture there, too.

We love CPU design, and this is an interesting chance to contribute to an open CPU while there are still interesting things to do. If you need to start with something easier, plenty of small CPUs exist for educational purposes.

Organizing Components, The Easy Way

January 3, 2025 by 49 Comments

There’s an old joke: What do you get someone who has everything? A place to put it. For hackers like [Christian], everything is a hoard of priceless electronic components. His solution is using small zipper bags, either regular plastic or anti-static. These attach using hook and loop fastener to plastic binder sheets which then live in a binder. Combined with some custom printed labels and a few other tricks, it makes for a nice system, as you can see in the video below.

Honestly, we’ve done something similar before, using a binder with little pockets, but the bag and custom labels beat our system. He even has QR codes on some of them to locate data sheets easily. Seems like a barcode for inventory management might have been good, too.

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