Author: Zoe Skyforest

3700 Articles

Building RAM Expansions For The DEC Rainbow 100

September 14, 2023 by 3 Comments

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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Building A Rotating Display Plate From A Lazy Susan

September 14, 2023 by 9 Comments

A rotating table is a super nifty tool for all kinds of photography and videography purposes. [Handy Bear] built a super simple example using some parts from IKEA.

The build starts with a Snudda, which is IKEA’s version of a Lazy Susan. It’s fitted with a 3D-printed gear to allow it to be easily driven. The platter is then fitted to a 3D printed base, which also contains the drive electronics, and driven by a small brushed DC gear motor. An off-the-shelf speed controller was employed to allow the speed of the platter to be varied as required.

[Handy Bear] does a good job of explaining how to build the project properly while avoiding the usual pitfalls. In particular, he demonstrates how to fit the gear to the platter without getting it off-axis. We also appreciate a design that can be built virtually anywhere thanks to using commonly-available parts.

We’ve featured other rotating tables before, like this open-ended design that was built on a much larger scale. Video after the break.

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Machine Learning Robot Runs Arduino Uno

September 14, 2023 by 7 Comments

When we think about machine learning, our minds often jump to datacenters full of sweating, overheating GPUs. However, lighter-weight hardware can also be used to these ends, as demonstrated by [Nikodem Bartnik] and his latest robot.

The robot is charged with autonomously navigating a simple racetrack delineated by cardboard barriers. The robot is based on a two-wheeled design with tank-style steering. Controlled by an Arduino Uno, the robot uses a Slamtec RPLIDAR sensor to help map out its surroundings. The microcontroller is also armed with a Bluetooth link and an SD card for storage.

The robot was first driven around the racetrack multiple times under manual control, all the while collecting LIDAR data. This data was combined with control inputs to help create a data set that could be used to train a machine learning model. Feature selection techniques were used to refine down the data points collected to those most relevant to completing the driving task. [Nikodem] explains how the model was created and then refined to drive the robot by itself in a variety of race track designs.

It’s a great primer on machine learning techniques applied to a small embedded platform.

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Rocker Bogie Suspension: The Beloved Solution To Extra-Planetary Rovers

September 14, 2023 by 18 Comments

When navigating the vast and unpredictable expanses of outer space, particularly on the alien terrains of distant planets, smart engineering often underlies every major achievement. A paramount example of this is the rocker bogie suspension system. It’s an integral component of NASA’s Mars rovers and has become an iconic feature in its own right. Its success has seen the design adopted by the Indian space program and thousands of hobbyists in turn.

So, what exactly is it that makes rocker bogie suspension such a compelling design solution? Let’s dive into the engineering that makes these six-wheeled wonders so special.

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FPGA Runs IBM 5151 MDA Display

September 13, 2023 by 11 Comments

When it comes to driving a display, you can do all kinds of fancy tricks with microcontrollers to get an image up. Really, though, FPGAs are the weapon of choice for playing with these kinds of signals. [Ted Fried] put one to great work driving an ancient IBM 5151 MDA display, and shared his results on Hackaday.io.

The build relies on a Digilent Arty Z7-20 SOC FPGA development board, which has a beefy 600 MHz ARM processor on board. It also packs 500 MB of DRAM—more than enough for storing pixel data for an ancient display.

To drive the old display, [Ted] whipped up a state machine on the FPGA. It’s tasked with fetching display data from RAM and creating the appropriate timings for the MDA display interface. The images are stored directly in an array in C code running on the ARM core. From there, they are copied into the FPGA’s RAM for trucking out to the display. The 720×350 images are stored as 1 bit per pixel, and are created by converting the original JPEGs into single-bit bitmaps in GIMP, before final conversion into a C code array via utility of [Ted’s] own design.

If you’ve ever wanted to display your images in resplendent amber or green, then this could be the project for you. It’s also just a great way to learn about using FPGAs and interfacing with alternative display technologies. If you’ve been whipping up your own retro display hacks, don’t hesitate to drop us a line.

Paper Punching Machine Looks Like Cute Piece Of Computer History Past

September 13, 2023 by 23 Comments

Computing used to run on punch cards. Great stacks of cards would run middling programs, with data output onto more punched cards in turn. [Nii] has built a machine in this vein, capable of punching binary into paper tape. 

The machine is run by a stepper motor, which is charged with feeding the paper tape through the machine in steady steps. A series of vertically-actuated solenoids punch holes in the paper tape as directed. The machine buzzes and clicks away like the best electromechanical computing devices of the mid-century era.

To what end, we couldn’t possibly say. One user noted the machine was punching seemingly random binary into the paper tape, and [Nii] has not provided any explanation as to the machine’s higher purpose. Regardless, whatever it is doing, it looks like it’s doing it well. Feel free to speculate in the comments.

Impressively, the petite device will be demonstrated at MF-TOKYO, the 7th Annual Metal Forming Fair in Tokyo this year. We’re sure the clickity-clack will be muchly appreciated in person.  Video after the break.

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3D Printed RC Car Is Geared For Speed

September 13, 2023 by 7 Comments

You can always go out and buy an RC car off the shelf. However, it’s readily achievable to print your own design that has many of the features of off-the-shelf models, as demonstrated by [Jinan].

[Jinan] set about creating a rear-wheel-drive design with a low center of gravity for good handling. Two large 5.2 Ah batteries slung low in the chassis help keep the car planted when cornering. [Jinan] also developed a double-wishbone suspension setup up front to handle bumps with ease.

With his eyes on top speed, [Jinan] needed a drivetrain that could handle sustained high RPM operation without failure. During the development process, [Jinan] spent plenty of time learning about the mathematics behind gear shapes before relying on a built-in CAD generator to do the job for him. Armed with proper gearing, he focused on making sure the driveshafts and other links wouldn’t fail at speed.

[Jinan] doesn’t shy away from diving into the engineering of his design, analyzing failures and improving on his designs along the way. It’s no surprise his design was able to reach 66 km/h (41 MPH) after his rigorous development process.  It’s compelling watching, and a great way to learn something.

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