Programmable Ruler Keeps 1970’s Computing Alive

A ruler seems like a pretty simple device; just a nice straight piece of material with some marks on it. There are some improvements out there to the basic design, like making it out of something flexible or printing a few useful crib notes and formulas on it so you have a handy reference. But for the most part, we can all agree that ruler technology has pretty much plateaued.

Well, not if [Brad] has anything to say about it. His latest creation, the Digirule2, is essentially an 8-bit computer like those of the 1970’s that just so happens to be a functional ruler as well. Forget lugging out the Altair 8800 next time you’re in the mood for some old school software development, now you can get the same experience with a piece of hardware that lives in your pencil cup.

Even if you’ve never commanded one of the blinkenlight behemoths that inspired the Digirule2, this is an excellent way to get some hands-on experience with early computer technology. Available for about the cost of a large pizza on Tindie, it represents one of the easiest and most cost-effective ways to tell your friends that as a matter of fact you have programmed a computer in binary.

The Digirule2 is powered by a Microchip PIC18F43K20, and is programmed by punching binary in one byte at a time with a bank of eight tactile switches. To make things a little easier, programs can be saved to the internal EEPROM and loaded back up just as easily thanks to the handy buttons next to the power switch. Now all you’ve got to do is figure out what all those blinking LEDs mean, and you’ll be in business.

The original Digirule was a logic gate simulator that we first covered back in 2015. We’re always happy to see projects grow and evolve over time, and think this new retro-computer themed variant is going to be quite popular with those who still love toggle switches and blinking lights.

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This Blinken Grid Is All Analog

The personal computers of today are economical with their employ of the humble LED. A modern laptop might have a power LED, and a hard drive indicator if you’re lucky. It was the mainframes of the ’60s and ’70s that adhered to the holy Doctrine of Blinken, flickering lamps with abandon to indicate machine activity to the skilled operators of yore. [Matseng] wanted to recreate this aesthetic, and went about it in an entirely analog fashion.

The project is built around an 8×8 LED grid, that was soldered up using a 3D printed jig for dimensional accuracy. Fitted to each column is a PNP flip flop that pulls the column to VCC, while each row has an NPN flip flop which pulls it to ground. Due to variances in component values and tolerances, the oscillators are all out of sync, leading to a remarkably pleasing blinkenlights effect.

We’re a big fan of the raw aesthetic, but [Matseng] has also fitted the grid with a diffuser which more clearly represents that vintage computer aesthetic. We’re a big fan of the blinken here, such as this loving recreation of the PDP-8/I. Video after the break. Continue reading “This Blinken Grid Is All Analog”

Getting Started with Blinking Lights on Old Iron

If you ever go to a computer history museum, you’ll be struck by how bland most modern computers look. Prior to 1980 computers had lights and switches, and sometimes dials and meters. Some had switchboard-like wiring panels and some even had oscilloscope-like displays. There’s something about a machine with all those switches and lights and displays that gets your hacker juices flowing. Have you ever wanted to get started in retrocomputing? Is it difficult? Do you need a lot of money? That depends on what your goals are.

There are at least three ways you can go about participating in retrocomputing: You can pony up the money to buy actual antique computers, you can build or buy old computers recreated with anywhere from zero to one hundred percent of period-authentic components, or you can experiment with emulators that run on a modern computer. As a hybrid of the second and third option there are also emulations in FPGAs.

You can see that the first option can be very expensive and you will probably have to develop a lot of repair and restoration skills. Watching [Mattis Lind] twiddle the bits on an actual PDP-8 in the clip above is great, but you’ll need to work up to it. The two techniques which get you going without the original hardware don’t have to break the bank or even cost anything presuming you already have a PC.

Although some sneer at emulation, for some machines it is almost the only way to go. You couldn’t buy the original EDSAC, for example. It is also a good way to get started without a lot of expense or risk. But regardless of how you do it, there’s one thing in common: you have to know how to operate the thing.

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Use Ruby to Make Any Window A Blinken Window

[Akhil Stanislavose] wanted to spice up his window decorations for the holidays. Inspired by blinkenlights, he decided to make his front window interactive. The Blinken Window is a grid of 6 x 10 programmable LEDs running on a Raspberry Pi. Since a RasPi doesn’t have enough GPIO pins for 60 LEDs, [Akhil] built an expander board using 8 daisy chained standard CD4094 (74HC595 could also be used) shift registers to accommodate them.

[Akhil] designed a PCB to replace the expander board for future use. It is modular in nature so that many of them can be connected together to provide as many outputs as one needs, allowing any size window to become a Blinken Window. The PCBs are still being fabricated, but the Eagle files are available for download (zip file). Ruby was used to implement the API. You can find the project files on GitHub, which also features a simulator that you can run on your computer to see how an animation or game will end up looking on the window. In the demo video, [Akhil] demonstrates how you can use the Blinken Window to play a version of Pong using your smartphone as the controller. [Akhil] has also provided a few basic animation examples that can be expanded upon. We’d enjoy seeing an implementation of Tetris. There’s so many fun ways to turn regular windows into dynamic displays, we’re starting to look scornfully at our own lazy, air leaking windows.

See the Blinken Window in action after the break.

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Turning LEDs into a camera

[Udo] figured out how to turn a bunch of LEDs into a very low resolution camera.

The build is based around [Udo]’s Blinkenlight shield he’s been developing over the past year. The camera operates under the idea that there’s really not much difference between a LED and a photodiode; LEDs can do light emission and detection. In actuality, the LED ‘camera’ isn’t all that different from a linear CCD array, the type of image sensor in flatbed scanners.

After connecting his Blinkenlight shield to his Arduino and computer, [Udo] wrote a sketch that would capture 17 values from his LED camera. These values are shot over the serial connection where high levels of light show up as smaller numbers and low light levels are understood as larger numbers.

[Udo] has been doing a lot of other cool stuff with his Blinkenlight shield, like a persistence of vision experiment and pretending to be [Michael Knight]. Check out the video after the break for a demo of [Udo]’s linear LED camera.

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