C Compiler Exists Entirely In Vim

July 7, 2024 by Donald Papp 36 Comments

8cc.vim is a C compiler that exists as pure Vimscript. Is it small? It sure is! How about fast? Absolutely not! Efficient? Also no. But does it work and is it neat? You betcha!

Ever typed :wq to write the buffer and exit in Vim? When you do that, you’re using Vimscript. Whenever one enters command mode : in Vim, one is in fact using a live Vimscript interpreter. That’s the space in which this project exists and does its magic. Given enough time, anyway.

Vimscript itself was created by [Bram Moolenaar] in 1991. The idea was to execute batches of vim commands programmatically. It’s been used for a variety of purposes since then.

8cc is a lightweight C compiler that has been supplanted by chibicc, but that doesn’t matter much because as author [rhysd] admits, this is really just a fun concept project more than anything. It may take twenty minutes or more to compile “hello world”, but doing it entirely from within Vim is a trip.

Custom Microcode Compiler, Made In Google Sheets

July 7, 2024 by Donald Papp 12 Comments

When homebrewing a CPU, one has to deal with microcode. Microcode is the low-level nuts and bolts of how, precisely, a CPU executes instructions (like opcodes) and performs functions such as updating the cycle counter or handling interrupt requests. To make this task easier, [Bob Alexander] created a microcode compiler built in Google Sheets to help with his own homebrew work, but it’s flexible and configurable enough to be useful to others, as well.

A CPU’s microcode usually lives in read-only memory, and writing the microcode is only one step in the journey. [Bob]’s tool compiles his microcode into files that can be burned into memory (multiple EEPROM chips, in [Bob]’s case) or used as a Verilog program in the case of implementing the CPU in an FPGA. It’s configurable enough to be adapted for other homebrew CPU projects, though one would of course have to re-write the microcode portion.

A read-only version of the spreadsheet makes for some fun browsing, and if it piques your interest enough to get a copy of your own complete with the compiler script, you can do that here. It uses Google Sheets, and writes the output files into one’s Google Drive.

This kind of low-level project really highlights the finer points of just how the hard work of digital computing gets done. A good example is the Gigatron which implemented a RISC CPU using only microcode, memory, and logic gates in the late 70s. We’ve even seen custom microcode used to aid complex debugging.

Useless Robot Gets Cute, Has Personality

July 4, 2024 by Donald Papp 4 Comments

Useless robots (or useless machines) are devices that, when switched on, exist only to turn themselves back off. They are fun and fairly simple builds that are easy to personify, and really invite customization by their creators. Even so, [tobychui]’s Kawaii Useless Robot goes above and beyond in that regard. Not only will his creation dutifully turn itself off, but if the user persists in engaging it, Kawaii Useless Robot grows progressively (and adorably) upset which ultimately culminates in scooting about and trying to run away.

If anything, it gets *cuter* when upset.

This is actually a ground-up re-imagining of an original work [tobychui] saw from a Japanese maker twelve years ago. That original Kawaii Useless Robot did not have any design details, so [tobychui] decided to re-create his own.

Behind the laser-cut front panel is a dot matrix LED display made up of eight smaller units, and inside are a total of four motors, an ESP32 development board, and supporting electronics. A neat touch is the ability to allow connections over Wi-Fi for debugging or remote control. The project page has some nice photos of the interior that are worth checking out. It’s a very compact and efficient build!

Watch it in action in the video (embedded below) which also includes a tour of the internals and a thorough description of the functions.

Inspired to make your own useless machine? Don’t be afraid to re-invent the whole concept. For example, we loved the one that physically spins the switch and the clock that falls to the floor when it detects someone looking at it. That last one is a close relative of the clock that displays the wrong time if and only if someone is looking.

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Peering Into The Black Box Of Large Language Models

July 3, 2024 by Donald Papp 35 Comments

Large Language Models (LLMs) can produce extremely human-like communication, but their inner workings are something of a mystery. Not a mystery in the sense that we don’t know how an LLM works, but a mystery in the sense that the exact process of turning a particular input into a particular output is something of a black box.

This “black box” trait is common to neural networks in general, and LLMs are very deep neural networks. It is not really possible to explain precisely why a specific input produces a particular output, and not something else.

Why? Because neural networks are neither databases, nor lookup tables. In a neural network, discrete activation of neurons cannot be meaningfully mapped to specific concepts or words. The connections are complex, numerous, and multidimensional to the point that trying to tease out their relationships in any straightforward way simply does not make sense.

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A DIY Proximity Sensor, Using Just Scrap Parts And Software

July 1, 2024 by Donald Papp 7 Comments

[mircemk] shows how to create a simple non-contact proximity sensor using little more than an Arduino Nano board, and a convenient software library intended to measure the value of capacitors.

The prototype has a threshold set via potentiometer for convenience.

The basic idea is that it’s possible to measure a capacitor’s capacitance using two microcontroller pins and the right software, so by using a few materials to create an open-style capacitor, one can monitor it for changes and detect when anything approaches enough to alter its values past a given threshold, creating a proximity sensor.

The sensor shown here is essentially two plates mounted side-by-side, attached to an Arduino Nano using the Capacitor library which uses just two pins, one digital and one analog.

As configured, [mircemk]’s sensor measures roughly thirty picofarads, and that value decreases when approached by something with a dielectric constant that is different enough from the air surrounding the sensor. The sensor ignores wood and plastic, but an approaching hand is easily detected. The sensor also detects liquid water with similar ease, either in the form of pooled liquid, or filled bottles.

We’ve also seen a spring elegantly used as a hidden touch sensor that works through an enclosure’s wall by using similar principles, so the next time you need a proximity or touch-sensitive sensor in a project, reaching for the junk box might get you where you need to go. Watch [mircemk]’s sensor in action in the video, just below the page break.

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Bats Can No Longer Haunt Apple VR Headsets Via Web Exploit

June 26, 2024 by Donald Papp 33 Comments

Bug reporting doesn’t usually have a lot of visuals. Not so with the visionOS bug [Ryan Pickren] found, which fills a user’s area with screeching bats after visiting a malicious website. Even better, closing the browser doesn’t get rid of them! Better still? Doesn’t need to be bats, it could be spiders. Fun!

The bug has been fixed, but here’s how it worked: the Safari browser build for visionOS allowed a malicious website to fill the user’s 3D space with animated objects without interaction or permission. The code to trigger this is remarkably succinct, and is actually a new twist on an old feature: Apple AR Quick Look, an HTML-based feature for rendering 3D augmented reality content in Safari.

Leveraging this old feature is what lets an untrusted website launch an arbitrary number of animated 3D objects — complete with sound — into a user’s virtual space without any interaction from the user whatsoever. The icing on the cake is that Quick Look is a separate process, so closing Safari doesn’t get rid of the pests.

Providing immersive 3D via a web browser is a valuable way to deliver interactive content on both desktops and VR headsets; a good example is the fantastic virtual BBC Micro which uses WebXR. But on the Apple Vision Pro the user is always involved and there are privacy boundaries that corral such content. Things being launched into a user’s space in an interaction-free way is certainly not intended behavior.

The final interesting bit about this bug (or loophole) was that in a way, it defied easy classification and highlights a new sort of issue. While it seems obvious from a user experience and interface perspective that a random website spawning screeching crawlies into one’s personal space is not ideal, is this a denial-of-service issue? A privilege escalation that technically isn’t? It’s certainly unexpected behavior, but that doesn’t really capture the potential psychological impact such bugs can have. Perhaps the invasion of personal space and user boundaries will become a quantifiable aspect of bugs in these new platforms. What fun.

Torment Poor Milton With Your Best Pixel Art

June 25, 2024 by Donald Papp 7 Comments

One of the great things about new tech tools is just having fun with them, like embracing your inner trickster god to mess with ‘Milton’, an AI trapped in an empty room.

Milton is trapped in a room is a pixel-art game with a simple premise: use a basic paint interface to add objects to the room, then watch and listen to Milton respond to them. That’s it? That’s it. The code is available on the GitHub repository, but there’s also a link to play it live without any kind of signup or anything. Give it a try if you have a few spare minutes.

Under the hood, the basic loop is to let the user add something to the room, send the picture of the room (with its new contents) off for image recognition, then get Milton’s reaction to it. Milton is equal parts annoyed and jumpy, and his speech and reactions reflect this.

The game is a bit of a concept demo for Open Souls whose “thing” is providing AIs with far more personality and relatable behaviors than one typically expects from large language models. Maybe this is just what’s needed for AI opponents in things like the putting game of Connect Fore! to level up their trash talking.