Get Your Lisp On With The Dune Shell

September 20, 2024 by Dave Rowntree 10 Comments

Lisp is one of those programming languages that seems to keep taunting us for not learning it properly. It is still used for teaching functional languages today. [Adam McDaniel] has an obvious fondness for this fifty-year-old language and has used it in several projects, including their own shell, Dune.

Dune is a shell designed for powerful scripting. Think of it as an unholy combination of bash and Lisp.

Dune is designed to be highly customisable, allowing you to create a super-optimised workstation for your admin and programming tasks. [Adam] describes the front end for Dune as having turned up the cosiness dial to eleven, and we can see that. A cosy home is personalised, and Dune lets you customise everything.

Dune is a useable functional programming environment with a reasonably complete standard library to back it up, which should simplify some of the more complicated sysadmin tasks. [Adam] says the language also supports a few metaprogramming concepts, such as a quote operator, operator overloading, and macro programming. It’s difficult to describe much more about what you can do with Dune, as it’s a general-purpose programming language wrapped in a shell. The possibilities are endless, and [Adam] is looking forward to seeing what you lot out there do with his project!

The shell can be personalised by editing the prelude file, which allows you to overload functions for the prompt text, the incomplete prompt text (so you can implement intelligent completion options), and a function that deals with the formatting of the command response text. [Adam] gives us his personal prelude file, which defines many helper functions displaying useful things such as the current weather, a calendar, and an ASCII art cat. You never know when that might come in handy. This file is written in Lisp, so we reckon that’s where many people will start as they come up the Lisp (re)learning curve before embarking on more involved automation. Dune was written in Rust, so you need that infrastructure to install it with Cargo.

As we said earlier, Lisp is not a new language. We found a hack for porting a Lisp interpreter to any old language and also running Lisp bare metal on a Lisp machine. Finally, [Al] takes a look at some alternative shells.

Reverse Engineering A Keyboard Driver Uncovers A Self-Destruct Code

September 19, 2024 by Dave Rowntree 22 Comments

Should you be able to brick a keyboard just by writing a driver to flash the lights on it? We don’t think so either. [TheNotary] got quite the shock when embarking on a seemingly straightforward project to learn C++ on the x86-64 architecture with Windows and sent it straight to Silicon Heaven with only a few seemingly innocent USB packets.

The project was a custom driver for the XVX S-K80 mechanical keyboard, aiming to flash LED patterns across the key LEDs and perhaps send custom images to the integrated LCD. When doing this sort of work, the first thing you need is the documentation of the communications protocols. Obviously, this was not an option with a closed-source project, so the next best thing is to spy on the existing Windows drivers and see how they worked. Using Wireshark to monitor the USB traffic whilst twiddling with the colour settings, it was clear that communications were purely over HID messages, simplifying subsequent analysis. Next, they used x32dbg (now x64dbg, but whatever) to attach to the existing driver process and trap a few interesting Windows system calls. After reading around the Windows API, a few candidate functions were identified and trapped. This gave them enough information to begin writing code to reproduce this behaviour. Then things got a bit odd.

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Embossing Graphics By 3D Printing On Wood

September 19, 2024 by Dave Rowntree 9 Comments

Embossing (making raised shapes) and debossing (making sunken shapes) on 3D-printed surfaces is not a new idea; we do it all the time. [Cory] from Vancouver Hack Space was playing around with 3D printing on wood, and came up with the idea of creating raised tactile surfaces using a simple transfer process.

We don’t often try to print directly onto a wooden surface for various reasons, but [Cory] wanted to give it a go. They hoped to get some grain patterns to transfer to the surface, but as they say in the blog entry, the beauty of wood patterns is in the colouration, which doesn’t transfer. Next, they laser etched a logo into the wood surface to see how well that would transfer. It did create a discernable raised impression, but they forgot to mirror the image (oops!) and relevel the bed, so the results are less impressive than they could be. Still, it’s another useful technique to consider.

Embossing is the process by which braille sheets are made. This DIY braille encoder is pretty sweet. Of course, the process can simply be decorative. Here’s how to use a laser cutter to create your own embossing seals. The traditional way to emboss paper for a fancy effect was to use embossing powder to selectively change the properties of drying paper. But how can you make the stuff for cheap?

Upgraded Raster Laser Projector Goes RGB

September 18, 2024 by Dave Rowntree 10 Comments

We’ve covered a scanning laser project by Ben Make’s Everything last year, and now he’s back with a significant update. [Ben]’s latest project now offers a higher resolution and RGB lasers. A couple of previous versions of the device used the same concept of a rotating segmented mirror synchronised to a pulsed laser diode to create scanlines. When projected onto a suitable surface, the distorted, pixelated characters looked quite funky, but there was clearly room for improvement.

More scanlines and a faster horizontal pixel rate

The previous device used slightly inclined mirrors to deflect the beam into scanlines, with one mirror per scanline limiting the vertical resolution. To improve resolution, the mirrors were replaced with identically aligned mirrors of the type used in laser printers for horizontal scanning. An off-the-shelf laser galvo was used for vertical scanning, allowing faster scanning due to its small deflection angle. This setup is quicker than then usual vector galvo application, as the smaller movements require less time to complete. Once the resolution improvement was in hand, the controller upgrade to a Teensy 4 gave more processing bandwidth than the previous Arduino and a consequent massive improvement in image clarity.

Finally, monochrome displays don’t look anywhere near as good as an RGB setup. [Ben] utilised a dedicated RGB laser setup since he had trouble sourcing the appropriate dichroic mirrors to match available lasers. This used four lasers (with two red ones) and the correct dichroic mirrors to combine each laser source into a single beam path, which was then sent to the galvo. [Ben] tried to find a DAC solution fast enough to drive the lasers for a proper colour-mixing input but ended up shelving that idea for now and sticking with direct on-off control. This resulted in a palette of just seven colours, but that’s still a lot better than monochrome.

The project’s execution is excellent, and care was taken to make it operate outdoors with a battery. Even with appropriate safety measures, you don’t really want to play with high-intensity lasers around the house!

Here’s the previous version we covered, a neat DIY laser galvo using steppers, and a much older but very cool RGB vector projector.

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Exploring TapTo NFC Integration On The MiSTer

September 15, 2024 by Dave Rowntree 14 Comments

[Ken] from the YouTube channel What’s Ken Making is back with another MiSTer video detailing the TapTo project and its integration into MiSTer. MiSTer, as some may recall, is a set of FPGA images and a supporting ecosystem for the Terasic DE10-Nano FPGA board, which hosts the very capable Altera Cyclone V FPGA.

The concept behind TapTo is to use NFC cards, stickers, and other such objects to launch games and particular key sequences. This allows an NFC card to be programmed with the required FPGA core and game image. The TapTo service runs on the MiSTer, waiting for NFC events and launching the appropriate actions when it reads a card. [Ken] demonstrates many such usage scenarios, from launching games quickly and easily with a physical ‘game card’ to adding arcade credits and even activating cheat codes.

As [Ken] points out, this opens some exciting possibilities concerning physical interactivity and would be a real bonus for people less able-bodied to access these gaming systems. It was fun to see how the Nintendo Amiibo figures and some neat integration projects like the dummy floppy disk drive could be used.

TapTo is a software project primarily for the MiSTer system, but ports are underway for Windows, the MiSTex, and there’s a working Commodore 64 game loader using the TeensyROM, which supports TapTo. For more information, check out the TapTo project GitHub page.

We’ve covered the MiSTer a few times before, but boy, do we have a lot of NFC hacks. Here’s an NFC ring and a DIY NFC tag, just for starters.

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Archiving Data On Paper Using 2D Images

September 15, 2024 by Dave Rowntree 43 Comments

It seems like only yesterday we covered a project using QR codes to archive data on paper (OK, it was last Thursday), so here’s another way to do it, this time with a dedicated codec using the full page. Optar or OPTical ARchiver is a project capable of squeezing a whopping 200 Kb of data onto a single A4 sheet of paper, with writing and reading achieved with a standard laser printer and a scanner. It’s a bit harder than you might think to get that much data on the page, given that even a 600 DPI printer can’t reliably place every dot each time. Additionally, paper is rarely uniform at the microscopic scale, so Optar utilizes a forward error-correcting coding scheme to cater for a little irregularity in both printing and scanning.

The error-correcting scheme selected was an Extended Golay code (24, 12, 8), which, interestingly, was also used for image transmission by the NASA Voyager 1 and 2 missions. In information theory terms, this scheme has a minimum Hamming Distance of 8, giving detection of up to seven bit errors. This Golay code implementation is capable of correcting three-bit errors in each 24-bit block, with 12 bits available for payload. That’s what the numbers in those brackets mean.

Another interesting problem is paper stretch during printing. A laser printer works by feeding the paper around rollers, some of which are heated. As a printer wears or gets dirty, the friction coefficient along the rollers can vary, leading to twisting and stretching of the paper during the printing process. Water absorbed by the paper can also lead to distortion. To compensate for these effects, Optar regularly inserts calibration targets throughout the bit image, which are used to locally resynchronize the decoding process as the image is processed. This is roughly similar to how the alignment patterns work within larger QR codes. Finally, similar to the position detection targets (those square bits) in QR codes, Optar uses a two-pixel-wide border around the bit image. The border is used to align to the corners well enough to locate the rows of bits to be decoded.

In the distant past of last week, we covered a similar project that uses QR codes. This got us thinking about how QR codes work, and even if encoding capacity can be increased using more colors than just black and white?

Thanks to [Petr] for the tip!

Taking Back The Internet With The Tildeverse

September 14, 2024 by Dave Rowntree 24 Comments

For many of us of a particular vintage, the internet blossomed in the ’90s with the invention of the Web and just a few years of development. Back then, we had the convenience of expression on the WWW and the backup of mature services such as IRC for all that other stuff we used to get up to. Some of us still hang out there. Then something happened. Something terrible. Big-commerce took over, and it ballooned into this enormously complex mess with people tracking you every few seconds and constantly trying to bombard you with marketing messages. Enough now. Many people have had enough and have come together to create the Tildeverse, a minimalist community-driven internet experience.

A collaborative Minecraft server hosted on a Tilde site

Tilde, literally ‘ ~ ‘, is your home on the internet. You can work on your ideas on a shared server or run your own. Tilde emphasises the retro aesthetic by being minimal and text-orientated. Those unfamiliar with a command line may start getting uncomfortable, but don’t worry—help is at hand. The number of activities is too many to list, but there are a few projects, such as a collaborative Sci-Fi story, a radio station, and even a private VoIP server. Gamers are catered for as long as you like Minecraft, but we think that’s how it should go.

The Tildeverse also supports Gopher and the new Gemini protocol, giving some people a few more options with which to tinker. The usual method to gain access is to first sign up on a server, then SSH into it; you’re then taken to your little piece of the internet, ready to start your minimalist journey into the Tildeverse.

A couple of videos after the break go into much more detail about the whys and hows of the Tildeverse and are worth a chunk of your time.

We’ve talked about the ‘small web’ before. Here’s our guide to Gemini.

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