I did a “lecture”/“workshop” about this at work today. 16-bit DOS, real mode. 💾 Pretty cool and the audience (devs and sysadmins) seemed quite interested. 🥳

• People used the Intel docs to figure out the instruction encodings.
  
• Then they wrote a little DOS program that exits with a return code and they used uhex in DOSBox to do that. Yes, we wrote a COM file manually, no Assembler involved. (Many of them had never used DOS before.)
  
• DEBUG from FreeDOS was used to single-step through the program, showing what it does.
  
• This gets tedious rather quickly, so we switched to SVED from SvarDOS for writing the rest of the program in Assembly language. nasm worked great for us.
  
• At the end, we switched to BIOS calls instead of DOS syscalls to demonstrate that the same binary COM file works on another OS. Also a good opportunity to talk about bootloaders a little bit.
  
• (I think they even understood the basics of segmentation in the end.)
  

The 8086 / 16-bit real-mode DOS is a great platform to explain a lot of the fundamentals without having to deal with OS semantics or executable file formats.

Now that was a lot of fun. 🥳 It’s very rare that we do something like this, sadly. I love doing this kind of low-level stuff.

Saw this on Mastodon:

https://racingbunny.com/@mookie/114718466149264471

18 rules of Software Engineering

1. You will regret complexity when on-call
   
2. Stop falling in love with your own code
   
3. Everything is a trade-off. There’s no “best” 3. Every line of code you write is a liability 4. Document your decisions and designs
   
4. Everyone hates code they didn’t write
   
5. Don’t use unnecessary dependencies
   
6. Coding standards prevent arguments
   
7. Write meaningful commit messages
   
8. Don’t ever stop learning new things
   
9. Code reviews spread knowledge
   
10. Always build for maintainability
    
11. Ask for help when you’re stuck
    
12. Fix root causes, not symptoms
    
13. Software is never completed
    
14. Estimates are not promises
    
15. Ship early, iterate often
    
16. Keep. It. Simple.
    

Solid list, even though 14 is up for debate in my opinion: Software can be completed. You have a use case / problem, you solve that problem, done. Your software is completed now. There might still be bugs and they should be fixed – but this doesn’t “add” to the program. Don’t use “software is never done” as an excuse to keep adding and adding stuff to your code.

Okay, here’s a thing I like about Rust: Returning things as Option and error handling. (Or the more complex Result, but it’s easier to explain with Option.)

fn mydiv(num: f64, denom: f64) -> Option<f64> {
    // (Let’s ignore precision issues for a second.)
    if denom == 0.0 {
        return None;
    } else {
        return Some(num / denom);
    }
}

fn main() {
    // Explicit, verbose version:
    let num: f64 = 123.0;
    let denom: f64 = 456.0;
    let wrapped_res = mydiv(num, denom);
    if wrapped_res.is_some() {
        println!("Unwrapped result: {}", wrapped_res.unwrap());
    }

    // Shorter version using "if let":
    if let Some(res) = mydiv(123.0, 456.0) {
        println!("Here’s a result: {}", res);
    }

    if let Some(res) = mydiv(123.0, 0.0) {
        println!("Huh, we divided by zero? This never happens. {}", res);
    }
}

You can’t divide by zero, so the function returns an “error” in that case. (Option isn’t really used for errors, IIUC, but the basic idea is the same for Result.)

Option is an enum. It can have the value Some or None. In the case of Some, you can attach additional data to the enum. In this case, we are attaching a floating point value.

The caller then has to decide: Is the value None or Some? Did the function succeed or not? If it is Some, the caller can do .unwrap() on this enum to get the inner value (the floating point value). If you do .unwrap() on a None value, the program will panic and die.

The if let version using destructuring is much shorter and, once you got used to it, actually quite nice.

Now the trick is that you must somehow handle these two cases. You must either call something like .unwrap() or do destructuring or something, otherwise you can’t access the attached value at all. As I understand it, it is impossible to just completely ignore error cases. And the compiler enforces it.

(In case of Result, the compiler would warn you if you ignore the return value entirely. So something like doing write() and then ignoring the return value would be caught as well.)

We really are bouncing back and forth between flat UIs and beveled UIs. I mean, this is what old X11 programs looked like:

https://www.uninformativ.de/desktop/2025%2D06%2D21%2D%2Dkatriawm%2Dold%2Dxorg%2Dapps.png

Good luck figuring out which of these UI elements are click-able – unless you examine every pixel on the screen.

@movq@www.uninformativ.de That sounds great! (Well, they actually must have recorded the audio with a potato or so.) You talked about pledge(…) and unveil(…) before, right? I somewhere ran across them once before. Never tried them out, but these syscalls seem to be really useful. They also have the potential to make one really rethink about software architecture. I should probably give this a try and see how I can improve my own programs.

@prologic@twtxt.net I’m trying to call some libc functions (because the Rust stdlib does not have an equivalent for getpeername(), for example, so I don’t have a choice), so I have to do some FFI stuff and deal with raw pointers and all that, which is very gnarly in Rust – because you’re not supposed to do this. Things like that are trivial in C or even Assembler, but I have not yet understood what Rust does under the hood. How and when does it allocate or free memory … is the pointer that I get even still valid by the time I do the libc call? Stuff like that.

I hope that I eventually learn this over time … but I get slapped in the face at every step. It’s very frustrating and I’m always this 🤏 close to giving up (only to try again a year later).

Oh, yeah, yeah, I guess I could “just” use some 3rd party library for this. socket2 gets mentioned a lot in this context. But I don’t want to. I literally need one getpeername() call during the lifetime of my program, I don’t even do the socket(), bind(), listen(), accept() dance, I already have a fully functional file descriptor. Using a library for that is total overkill and I’d rather do it myself. (And look at the version number: 0.5.10. The library is 6 years old but they’re still saying: “Nah, we’re not 1.0 yet, we reserve the right to make breaking changes with every new release.” So many Rust libs are still unstable …)

… and I could go on and on and on … 🤣

OpenBSD has the wonderful pledge() and unveil() syscalls:

https://www.youtube.com/watch?v=bXO6nelFt-E

Not only are they super useful (the program itself can drop privileges – like, it can initialize itself, read some files, whatever, and then tell the kernel that it will never do anything like that again; if it does, e.g. by being exploited through a bug, it gets killed by the kernel), but they are also extremely easy to use.

Imagine a server program with a connected socket in file descriptor 0. Before reading any data from the client, the program can do this:

unveil("/var/www/whatever", "r");
unveil(NULL, NULL);
pledge("stdio rpath", NULL);

Done. It’s now limited to reading files from that directory, communicating with the existing socket, stuff like that. But it cannot ever read any other files or exec() into something else.

I can’t wait for the day when we have something like this on Linux. There have been some attempts, but it’s not that easy. And it’s certainly not mainstream, yet.

I need to have a closer look at Linux’s Landlock soon (“soon”), but this is considerably more complicated than pledge()/unveil():

https://landlock.io/

So I was using this function in Rust:

https://doc.rust-lang.org/std/path/struct.Path.html#method.display

Note the little 1.0.0 in the top right corner, which means that this function has been “stable since Rust version 1.0.0”. We’re at 1.87 now, so we’re good.

Then I compiled my program on OpenBSD with Rust 1.86, i.e. just one version behind, but well ahead of 1.0.0.

The compiler said that I was using an unstable library feature.

Turns out, that function internally uses this:

https://doc.rust-lang.org/std/ffi/struct.OsStr.html#method.display

And that is only available since Rust 1.87.

How was I supposed to know this? 🤨🫩

Having some fun with SIRDS this morning.

Image

What you should see: https://movq.de/v/dae785e733/disp.png

And the tutorial I used for my C program: https://www.ime.usp.br/~otuyama/stereogram/basic/index.html

For context, this is a funny
Interaction between an engineer and copilot on Microsoft’s core programming Language 🤣🤯

One of the nicest things about Go is the language itself, comparing Go to other popular languages in terms of the complexity to learn to be proficient in:

• Go: 25 keywords (Stack Overflow); CSP-style concurrency (goroutines & channels)
  
• Python 2: 30 keywords (TutorialsPoint); GIL-bound threads & multiprocessing (Wikipedia)
  
• Python 3: 35 keywords (Initial Commit); GIL-bound threads, asyncio & multiprocessing (Wikipedia, DEV Community)
  
• Java: 50 keywords (Stack Overflow); threads + java.util.concurrent (Wikipedia)
  
• C++: 82 keywords (Stack Overflow); std::thread, atomics & futures (en.cppreference.com)
  
• JavaScript: 38 keywords (Stack Overflow); single-threaded event loop & async/await, Web Workers (Wikipedia)
  
• Ruby: 42 keywords (Stack Overflow); GIL-bound threads (MRI), fibers & processes (Wikipedia)
  

@kat@yarn.girlonthemoon.xyz I only listened to you while going through my photos, so I did not pay very close attention. :-)

Since you have a proper server – haha, not just one – and hence are not limited, I suggest you learn a real programming language and don’t waste your time with this PHP mess. It might have improved a wee bit since I was a kid, but it felt like some hacked together shit. The defaults also were questionable at best, it was easier to hold it wrong than right. This stands testament to bad design and is especially terrible from a security point of view.

You’re right, programming is like any other craft. You only truly learn by actually doing it. And this just takes time. Very long time to master it. Or as close to as it gets. The more you know, the more you realize what else you don’t know (yet). It’s a never ending process. So, take it easy, don’t get discouraged, happy hacking and enjoy the endeavor! :-)

I have zero mental energy for programming at the moment. 🫤

I’ll try to implement the new hashing stuff in jenny before the “deadline”. But I don’t think you’ll see any texudus development from me in the near future. ☹️

@kat@yarn.girlonthemoon.xyz @prologic@twtxt.net Given that all these programs are super old (tar is from the late 1970ies), while trying to retain backwards-compatibilty, I’m not surprised that the UI isn’t too great. 🤔

find has quite a few pitfalls, that is very true. At work, we don’t even use it anymore in more complex scenarios but write Python scripts instead. find can be fast and efficient, but fewer and fewer people lack the knowledge to use it … The same goes for Shell scripting in general, actually.

@andros@twtxt.andros.dev Programming is art. You become good at art by practising your art. You learn artistic patterns by being inspired by and reading others art works. The most importance however is that you practise your art.

Nobody want to be a shitty programmer. The question is: Do you do anything not to not be one?
Reading blogs or social media and watching YouTube videos is fun. After them, your code may be a little better, of course. But you need a lot. You need to study! Read good books and study the code of other programmers, for example. Maybe work with a new language, architectures and paradigms. You need break the routine.

If you know Object-oriented programming, you learn functional programming.
If you know Model-View-Controller, you learn Model-View-ViewModel.
If you don’t know anything about architectures, you learn Clean Architecture, Hexagonal Architecture, etc.
If you know Python, you learn Ruby or Go.
If you know Clojure or Lisp… you don’t need to learn anything else. You are already a good programmer. Just kidding. You can learn Elixir or Scala.

Be a good programmer my friend.

@bender@twtxt.net Yes, you right. But is premium for more than that.
I use a feature I love a lot: customising different searches with different themes or links.
It’s easy to understand with an example. I have a search with the name “Django”. I set sources: Django documentation, stack overflow, topic “programming” and so on. It’s very quick to find Django solutions.
I also have another way to find my stuff: search my blog and repositories.
I had problems paying for the first mouths, now it’s a working tool for me.

Confession:

I’ve never found microblogging like twtxt or the Fediverse or any other “modern” social media to be truly fulfilling/satisfying.

The reason is that it is focused so much on people. You follow this or that person, everybody spends time making a nice profile page, the posts are all very “ego-centric”. Seriously, it feels like everybody is on an ego-trip all the time (this is much worse on the Fediverse, not so much here on twtxt).

I miss the days of topic-based forums/groups. A Linux forum here, a forum about programming there, another one about a certain game. Stuff like that. That was really great – and it didn’t even suffer from the need to federate.

Sadly, most of these forums are dead now. Especially the nerds spend a lot of time on the Fediverse now and have abandoned forums almost completely.

On Mastodon, you can follow hashtags, which somewhat emulates a topic-based experience. But it’s not that great and the protocol isn’t meant to be used that way (just read the snac2 docs on this issue). And the concept of “likes” has eliminated lots of the actual user interaction. ☹️

@lyse@lyse.isobeef.org Oh, no, this is vastly exaggerated. Neil deGrass Tyson says, the earth is smoother than a cue ball (billiard): https://www.youtube.com/watch?v=OMP5dNsZ-6k That would make for a very dull OpenGL program, though. 😂

@movq@www.uninformativ.de Agreed, finding the right motivation can be tricky. You sometimes have to torture yourself in order to later then realize, yeah, that was actually totally worth it. It’s often hard.

I think if you find a project or goal in general that these kids want to achieve, that is the best and maybe only choice with a good chance of positive outcome. I don’t know, like building a price scraper, a weather station or whatever. Yeah, these are already too advanced if they never programmed, but you get the idea. If they have something they want to build for themselves for their private life, that can be a great motivator I’ve experienced. Or you could assign ‘em the task to build their own twtxt client if they don’t have any own suitable ideas. :-)

Showing them that you do a lot of your daily work in the shell can maybe also help to get them interested in text-based boring stuff. Or at least break the ice. Lead by example. The more I think about it, the more I believe this to be very important. That’s how I still learn and improve from my favorite workmate today in general. Which I’m very thankful of.

Remembered a fun little “hello world” program I made in 2018:

https://movq.de/v/a1c4a819e6/vid.mp4

(It runs smoothly. My computer just isn’t fast enough for a smooth X11 screengrab at that resolution.)

We’re all old farts. When we started, there weren’t a lot of options. But today? I’d be completely overwhelmed, I think.

Hence, I’d recommend to start programming with a console program. As for the language, not sure. But Python is probably a good choice

That’s what I usually do (when we have young people at work who never really programmed before), but it doesn’t really “hit” them. They’ve seen so much, crazy graphics, web pages, it’s all fancy. Just some text output is utterly boring these days. ☹️ And that’s my problem: I have no idea how I could possibly spark some interest in things like pointers or something “low-level” like that. And I truly believe that you need to understand things like pointers in order to program, in general.

@xuu@txt.sour.is Hahaha, that’s cool! You were (and still are) way ahead of me. :-)

We started with a simple traffic light phase and then added pedestrian crossing buttons. But only painting it on the canvas. In our computer room there was an actual traffic light on the wall and at the very end of the school year our IT basics teacher then modified the program to actually control the physical traffic light. That was very impressive and completely out of reach for me at the time. That teacher pulled the first lever for me ending up where I am now.

@movq@www.uninformativ.de I started with Delphi in school, the book (that we never ever used even once and I also never looked at) taught Pascal. The UI part felt easy at first but prevented me from understanding fundamental stuff like procedures or functions or even begin and end blocks for ifs or loops. For example I always thought that I needed to have a button somewhere, even if hidden. That gave me a handler procedure where I could put code and somehow call it. Two or three years later, a new mate from the parallel class finally told me that this wasn’t necessary and how to do thing better.

You know all too well that back in the day there was not a whole lot of information out there. And the bits that did exist were well hidden. At least from me. Eventually discovering planet-quellcodes.de (I don’t remember if that was the original forum or if that got split off from some other board) via my best schoolmate was like finding the Amber Room. Yeah, reading the ITG book would have been a very good idea for sure. :-)

In hindsight, a console program without the UI overhead might have been better. At least for the very start. Much less things to worry about or get lost.

Hence, I’d recommend to start programming with a console program. As for the language, not sure. But Python is probably a good choice, it doesn’t require a lot of surrounding boilerplate like, say Java or Go. It also does exceptionally well in the principle of least surprise.

I should probably clarify: Which language/platform? Something graphical or web-based right from the beginning or do you start with a console program?

To the parents or teachers: How do you teach kids to program these days? 🤔

The End of Programming
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Programming in D: Tutorial and Reference
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TacOS: an x86_64 UNIX-like OS from scratch
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“How I use Kate Editor”
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Pipelining might be my favorite programming language feature
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CISA extends funding to ensure ‘no lapse in critical CVE services’
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Elliptical Python programming
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FreeDOS 1.4 released
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Sometimes, we spend months stuck in inertia, distracted by screens and routine. So I’d like to give you a simple reminder: creating-in whatever form-is what makes you feel alive.

The beauty of working on projects is not in their ‘success’, but in the simple act of working on them. Whether it’s writing, cooking, programming or redecorating the house: play with ideas without pressure, engage in an activity to test, fail and discover without judgement.

In the end, what remains is not a perfect product, but the satisfaction of completion and valuable lessons.

Find a project, no matter how small, and let it take you without expectations.

John Carmack on AI in game programming
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I’m a long-term mpd user (some 16+ years), but for $reasons I have to compile it myself now – and, boy, that is one heavy program. Takes several minutes to build. 😳

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Playing multimedia with Dillo
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@movq@www.uninformativ.de Yeah, most of the graphical applications are actually KDE programs:

• KMail – e-mail client
  
• Okular – PDF viewer
  
• Gwenview – image viewer
  
• Dolphin – file browser
  
• KWallet – password manager (I want to check out pass one day. The most annoying thing is that when I copy a password, it says that the password has been modified and asks me whether I want to save the changes. I never do, because the password is still the same. I don’t get it.)
  
• KPatience – card game
  
• Kdenlive – video editor
  
• Kleopatra – certificate manager
  

Qt:

• VLC – video player
  
• Psi – Jabber client (I happily used Kopete in the past, but that is not supported anymore or so. I don’t remember.)
  
• sqlitebrowser – SQLite browser
  

Gtk:

• Firefox – web browser
  
• Quod Libet – music player (I should look for a better alternative. Can’t remember why I had to move away from Amarok, was it dead? There was a fork Clementine or so, but I had to drop that for some unknown reason, too.)
  
• Audacity – audio editor
  
• GIMP – image editor
  

These are the things that are open right now or that I could think of. Most other stuff I actually do in the terminal.

In the past™, I used the Python KDE4 bindings. That was really nice. I could pass most stuff directly in the constructor and didn’t have to call gazillions of setters improving the experience significantly. If I ever wanted to do GUI programming again, I’d definitely go that route. There are also great Qt bindings for Python if one wanted to avoid the KDE stuff on top. The vast majority I do for myself, though, is either CLI or maybe TUI. A few web shit things, but no GUIs anymore. :-)

@lyse@lyse.isobeef.org

Although, most software I use is decentish in that regard.

Is that because you mostly use Qt programs? 🤔

I wish Qt had a C API. Programming in C++ is pain. 😢