Building RAM Expansions For The DEC Rainbow 100

It’s hard enough to get your hands on a forgotten computer from yesteryear. It’s even more difficult to get accessories like RAM expansions and graphics cards, because half the time they’re just discarded as random e-waste when they’re outside of their original context. [na103] has solved this problem for the DEC Rainbow 100 to a degree, by building new RAM expansions and graphics cards from scratch.

In the case of the RAM expansion, the design [na103] built is capable of boosting a Rainbow 100 computer to a full 896KB. This is more than other contemporary IBM machines like the 8088 XT, which had an architecture-enforced limit of 640 KB.  It was rebuilt from some notes and original DEC schematics.

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Rainbow DIP Switch Is The Coolest Way To Configure Your Project

Oftentimes, when programming, we’ll put configuration switches into a config file in order to control the behaviour of our code. However, having to regularly open a text editor to make changes can be a pain. This colorful little DIP switch dongle from [Glen Aikins] makes for a fun alternative solution.

Do want.

The build is simple, relying on a rainbow-colored 8-pin DIP switch as the core of the project. A PIC16F1459 then reads the position of the switches, with the 8-bit microcontroller doing the job of speaking USB to the host machine. The device enumerates as a USB HID device, and reports to the host machine when queried as to the state of its 8 switches. [Glen] used a basic C# app to show a digital representation of the switches on screen changing as per the real physical DIP switch plugged into the machine.

It’s a great tool for controlling up to 8 different parameters in a program you might be working on, without having to dive into your editor to change the relevant parts. Also, it bears noting that the rainbow design is simply very fetching and a cool thing to have plugged into your computer. It’s a more serious device than [Glen’s] hilarious 4-byte “solid state drive” that we saw recently, but we love them both all the same!

Sudden Death Rainbow Sorting Game Reveals Your True Colors

When [marzsman]’s eight-year-old daughter thought up a game they could play together involving rainbows, he was all ears. She is a certified rainbow expert, after all. They had a few R&D sessions and came up with a rainbow sorting speed trial game that looks fun to play and fairly easy to build.

Press that blue button on the side, and the RGB LEDs along the top are put in randomized order. The object of this game is simple — just sort the rainbow before the other player by pressing each LED’s corresponding arcade button. Whoever sorts faster is rewarded with a rainbow animation behind their set of way-cool clear buttons.

Inside the laser-cut box is an Espruino, which is a handy little microcontroller that speaks JavaScript. All of the arcade buttons are wired up as a key matrix. The astute among you have noticed there is six of everything, and that’s because indigo light is too hard to distinguish from blue. Check out the intense gameplay after the break.

If [marzsman]’s daughter wants to learn computer science, rainbows are good for that, too.

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Changing Color Under Pressure

When you saw the picture for this article, did you think of a peacock’s feather? These fibers are not harvested from birds, and in fact, the colors come from transparent rubber. As with peacock feathers, they come from the way light reflects off layers of differing materials, this is known as optical interference, and it is the same effect seen on oil slicks. The benefit to using transparent rubber is that the final product is flexible and when drawn, the interference shifts. In short, they change color when stretched.

Most of the sensors we see and feature are electromechanical, which has the drawback that we cannot read them without some form of interface. Something like a microcontroller, gauge, or a slew of 555 timers. Reading a single strain gauge on a torque wrench is not too tricky, but simultaneously reading a dozen gauges spread across a more complex machine such as a quadcopter will probably require graphing software to generate a heat map. With this innovation it could now be done with an on-board camera in real-time. Couple that with machine learning and perhaps you could launch Skynet. Or build a better copter.

The current proof-of-concept weaves the fibers into next-generation bandages to give an intuitive sense of how tightly a dressing should be applied. For the average first-aid responder, the rule is being able to slide a finger between the fabric and skin. That’s an easy indicator, but it only works after the fact whereas saying that the dressing should be orange while wrapping gives constant feedback.

Robo Rainbow Graffiti Machine

[mudlevel] built this rainbow graffiti producing robot for an art exhibit in San Diego. While there are no build details we can easily pick this apart from the pictures. Looks like the brains are an arduino, the drive is a power drill with the trigger removed, and a few other servos for firing the spray cans.  The counter weighted arm for creating the rainbow was a pretty good idea too. Watching this, we had an idea for a super simple purely mechanical way to do this that would be similar to a catapult.  You could use the motion of the trailer to “wind up” the counter balance with a simple ratcheting spool of string attached to the axle. Engage your spray cans and let the balance drop and you’re done.  Pedal on to re-wind the counterbalance for another rainbow.

Man Made Rainbow Uses ONLY Sunlight And Rainwater

This rainbow is and is not natural. It’s the product of rainwater and sunlight so in that respect it’s natural. But as you can see, it’s not raining. This is an art installation that uses captured rainwater, stored solar electricity, and irrigation equipment to float a heavy blanket of mist in the air. The prismatic effects of the suspended water particles separate the sunlight into various bands by wavelength and a rainbow springs into existence.

We’ve done this before with a garden hose in the back yard. It might be fun to try to build a version that recycles the water as this does, perhaps using a rain barrel as a reservoir. It would certainly be much easier than pulling off that water-based 3-D display we’ve been meaning to undertake.

[Thanks Xb0xGuru]