Commodore 64 Monitor Traces I/O Calls, Eases Debugging

February 18, 2022 by Donald Papp 7 Comments

Developing for the Commodore 64 can be a rewarding retrocomputing experience, and thanks to [Dave Van Wagner], things are easier with his C64 IO_Monitor project, which opens the door to logging and tracing Kernal I/O calls for closer inspection. That’s not a typo, by the way. Kernal is what handles the C64’s low-level OS routines. Amusingly, as the story goes, it did in fact originate as a misspelling of kernel, but the name stuck.

What [Dave]’s program does is trace and log all input and output calls going through Kernal, which includes just about any function one might imagine. Things like keyboard input, screen output, and disk or tape I/O are all dutifully counted and logged, allowing one to really peek under the hood at a low level when doing any kind of development work. This kind of tool has turned out to be pretty handy given [Dave]’s penchant for porting Commodore emulators to a variety of (sometimes unusual) platforms.

Interested in giving it a spin? Head to the project’s GitHub repository for all the necessary files as well as some usage details, and enjoy making debugging and development a little less opaque than it otherwise would be.

Hello (Many Quantum) World(s)

February 17, 2022 by Al Williams 9 Comments

Historically, the first program you write for a new computer language is “Hello World,” or, if you are in Texas, “Howdy World.” But with quantum computing on the horizon, you need something better. Like “Hello Many Worlds.” [IonQ] proposes what that looks like and then writes it in seven different quantum languages in a post you should check out.

Here’s the description of the simple program:

The basic quantum program we’ll write is simple. It creates a fully-entangled state between two qubits, and then measures this state. This state is sometimes called a Bell State, or Bell Pair, after physicist John Stewart Bell.

The measurement results for this program should give us 0 for both qubits or 1 for both qubits, in equal amounts. When running these, we’ll be able to tell that we’re running on real hardware because that’s not always what we get! These errors are what currently limit quantum computers, but the first steps to overcome this with quantum error correction have already begun.

Continue reading “Hello (Many Quantum) World(s)” →

Twist Promises Easier Quantum Programming

February 5, 2022 by Al Williams 17 Comments

We keep trying to learn more about quantum computers. But the truth is, the way we program quantum computers — or their simulators — today will probably not have much in common with how we program them in the future. Think about it. Programming your PC is nothing like programming the ENIAC. So we expect we’ll see more and more abstractions over the “bare metal” quantum computer. The latest of these is Twist, from MIT.

According to the paper (and the video, below), Twist expresses entangled data and processes in a way that traditional programmers can understand. The key concept is known as “purity” of expressions which helps the compiler determine if data is actually entangled with another piece of data or if any potential entanglement is extraneous. A pure expression only depends on qubits it owns, while a mixed expression may use qubits owned by other expressions.

Continue reading “Twist Promises Easier Quantum Programming” →

Hackaday Invades The FLOSS Weekly Podcast

February 2, 2022 by Tom Nardi No comments

Regular Hackaday readers will know that we’re big supporters of free/libre and open source software (FLOSS) around these parts. There’s an excellent chance you are too, as so many of the incredible projects you send our way make it a habit to share their innermost details, from firmware source code to the OpenSCAD files that generate its 3D printed components. So when our recently minted Editor in Chief [Elliot Williams] was invited to join This Week in Tech’s FLOSS Weekly podcast, he jumped at the chance to represent our little corner of the Internet to the wider world of open source aficionados. (Ed: The final version is now live! How did we get episode 666?!)

Hosted by [Doc Searls], FLOSS Weekly is known for its in-depth interviews with “the most interesting and important people in the Open Source and Free Software community”, so we hope the incursion by hacker rabble such as ourselves doesn’t taint their brand too much.

It’s live streamed every Wednesday at 12:30 PM Eastern / 9:30 AM Pacific / 17:30 UTC, which means that by the time this post hits the main page of the site, you’ve still got time to tune in. For those of you with gainful employment who can’t slack off for an hour or so in the middle of the workweek, the recorded version will be available afterwards for your time-shifted viewing and or listening pleasure.

[Elliot] will be joined by Hackaday writer and regular co-host of FLOSS Weekly [Jonathan Bennett], making this something of a Jolly Wrencher double-feature. [Jonathan] has been providing readers with a regular peek into the other type of hacking with his fantastic This Week in Security column, and is himself a devout FOSS supporter with a particular passion for GNU/Linux. We’re excited to listen in as the trio riffs on open source at the crossroads of hardware and software, not just because it promises to be an entertaining bit of programming, but because it’s a great opportunity to introduce the world of Hackaday to the wider open source audience.

A graph visualising approximation errors - the specific principle pictured is described well by the linked article

Time And Accuracy In Las ATMegas

January 31, 2022 by Arya Voronova 4 Comments

Do you ever have to ensure that an exact amount of time passes between two tasks in your microcontroller code? Do you know what’s the difference between precision and accuracy? Today, [Jim Mack] tells us about pushing timers and interrupts to their limits when it comes to managing time, while keeping it applicable to an ever-popular ATMega328P target! Every now and then, someone decides to push the frontiers of what’s possible on a given platform, and today’s rules is coding within constraints of an Arduino environment. However, you should check [Jim]’s post out even if you use Arduino as a swearword – purely for all of the theoretical insights laid out, accompanied by hardware-accurate examples!

This will be useful to any hacker looking to implement, say, motor encoder readings, signal frequency calculations, or build a gadget processing or modifying audio in real time. To give you a sample of this article, [Jim] starts by introducing us to distinctions between precision and accuracy, and then presents us with a seemingly simple task – creating exactly 2400 interrupts a second. As much as it might look straightforward, problems quickly arise when clock crystal frequency doesn’t cleanly divide by the sampling frequency that you have to pick for your application! This is just a taste of all the examples of hidden complexity presented, and they’re accompanied with solutions you can use when you eventually encounter one of these examples in your hacker pursuits. In the end, [Jim] concludes with links to other sources you can study if you ever need to dig deeper into this topic.

Keeping our projects true to the passage of time can be an issue, and we’ve been at it for ages – calibrating your RC oscillator is a rite of passage for any ATTiny project. If you ever decide to have an interrupt peripheral help you with timing issues, we’ve gone in-depth on that topic in the past, with a three-part series describing the benefits, the drawbacks and the edgecases of interrupts. Going for a more modern target? Our piece on using interrupts with STM32 is a great path for trying out tools of the modern age.

Apollo Guidance Computer Gets The Rust Treatment

January 29, 2022 by Tom Nardi 8 Comments

Seems like all the cool kids are rewriting legacy C programs in Rust these days, so we suppose it was only a matter of time before somebody decided to combine the memory-safe language with some of the most historically significant software ever written by way of a new Apollo Guidance Computer (AGC) emulator. Written by [Felipe], the Apache/MIT licensed emulator can run either ROM files made from the computer’s original rope core memory, or your own code written in AGC4 assembly language.

It’s worth noting that the emulator, called ragc, needs a bit of help before it can deliver that authentic Moon landing experience. Specifically, the code only emulates the AGC itself and stops short of recreating the iconic display and keyboard (DSKY) module. To interact with the programs running on the virtual AGC you’ll need to also install yaDSKY2, an open source project that graphically recreates the panel Apollo astronauts actually used to enter commands and get data from the computer.

Of course, the next step would be to hack in support for talking to one of the physical recreations of the DSKY that have graced these pages over the years. Given the limitations of the AGC, we’d stop short of calling such an arrangement useful, but it would certainly make for a great conversation starter at the hackerspace.

Thanks for the tip, [CJ].

Code Wrong: Expand Your Mind

January 29, 2022 by Elliot Williams 24 Comments

The really nice thing about doing something the “wrong” way is that there’s just so much variety! If you’re doing something the right way, the fastest way, or the optimal way, well, there’s just one way. But if you’re going to do it wrong, you’ve got a lot more design room.

Case in point: esoteric programming languages. The variety is stunning. There are languages intended to be unreadable, or to sound like Shakespearean sonnets, or cooking recipes, or hair-rock ballads. Some of the earliest esoteric languages were just jokes: compilations of all of the hassles of “real” programming languages of the time, but yet made to function. Some represent instructions as a grid of colored pixels. Some represent the code in a fashion that’s tantamount to encryption, and the only way to program them is by brute forcing the code space. Others, including the notorious Brainf*ck are actually not half as bad as their rap — it’s a very direct implementation of a Turing machine.

So you have a set of languages that are designed to be maximally unlike each other, or traditional programming languages, and yet still be able to do the work of instructing a computer to do what you want. And if you squint your eyes just right, and look at as many of them all together as you can, what emerges out of this blobby intersection of oddball languages is the essence of computing. Each language tries to be as wrong as possible, so what they have in common can only be the unavoidable core of coding.

While it might be interesting to compare an contrast Java and C++, or Python, nearly every serious programming language has so much in common that it’s just not as instructive. They are all doing it mostly right, and that means that they’re mostly about the human factors. Yawn. To really figure out what’s fundamental to computing, you have to get it wrong.