Bolide observation 2026-04-17 20:54 GMT+0200

Tonight I ovserved a bright bolide while on the garder in the evening. (Second time observing from a very similar spot). I've been fortunate to observe a number of bolides over the years. As has been my habit for a long time, I've reported my observation to the Czech Astronomical Institute through their Bolide reporting form.

Observing a bolide is always a special and fun experience, and trying to report them as precisely as possible is also fun. One constant problem is that when I take my phone out of my pocket, it only shows time in hours and minutes, so I cannot produce a more precise time information.

When you are out after sundown, keep you eyes open! Let's hope for more in the future!

Matfyzák's Story

Found a CD in my stash of old CDs with a copy of this legendary student film, Matfyzák's story from 1987.

This is a story about the life of a 'typical' student of the Faculty of mathematics and physics, Charles University, Prague. It used to be screened to all new students as late as 2002 when I joined the faculty. Not sure if it is still. I haven't found it on Youtube, so I posted it for archival purposes. I will probably upload the original file to my home page later.

Making progress?

I am working on adding actual file management operations to Navigator, the HelenOS file manager. Here's a sneak preview of New File operation. We can create and empty file or a zero-filled file of the specified size. Creating a large file can take time, so we need progress indication. And we need to do something about the command line, too.

Floppy Drive Lead Screw Lubrication

A question that often crops up (and has been bugging me for a very long time) is what is the correct type of lubricant to apply to floppy drive lead screws. Commonly mentioned lubricants are silicone grease and white lithium grease. But are these the correct ones? Clearly the safest and most correct option would be to use what the drive manufacturers recommend. It took me some time to dig up a floppy drive service manual has cleaning and lubrication instructions. It's the Micropolis Floppy Disk Subsystem Maintenance Manual. This has quite a bit of useful information. Firstly, we learn that both the head and the lead screw should be cleaned using IPA.

Lubricate the lead screw and the portion of the carriage that rides on the platen by applying a liberal portion of Saunders Magnalube Micropolis P/N 732-0001-6 to these surfaces.

Now of course an exact description of the P/N I was not able to find, but Saunders Magnalube are polyurea-based greases. So there you have it, black on white, use a polyurea-based grease. These can be easily found in an lubricants e-shop, no problem there. The internets say silicone grease should be safe, but may be challenging to apply and lithium grease may damage plastics. Take from that what you will, I think I will stick to manufacturer's recommendations. I have a plan for inspecting and probably cleaning a number of floppy drives (CF2, 3.5", 5.25") in the future, so this information is very handy. Let's grease some screws! ^_^

Sinclair ZX Spectrum +3 Unboxing!

Five years in the (not) making, and now it's finally here! Let's unwrap this very special package!

HelenOS 0.14.1 (Aladar) - Launch! Launch! Launch!

HelenOS 0.14.1 (Aladar) has been released. What's new? New way to launch applications. New multi-seat support. And more!

This what's new video took much extra effort, with the musical montage / intro. Now I am already hard at work on a PCI IDE driver and more fun stuff!

DOSMBoot teaser

Let's boot that kernel!

HelenOS 0.12.1 is here!

HelenOS 0.12.1 (Cathode) has been released. Let's have look at what's new.

I was glad to get this release out of the door. We've fixed a number nasty, longstarning, bugs. We've added a number of new features, including the task bar. With this out of the way, I can get back to work on more stuff!

Working on the Task Bar for HelenOS

Here's a little show and tell - an update on my progress implementing the Task Bar for HelenOS UI.

Partial Solar Eclipse 2022-10-25

Projected with a 10 cm refractor onto a sheet of paper and photographed with a handheld digital camera. Image cropped. No post-processing.

Tick tock! See the clock?

Do you know what time it is? Clock time!

Problems with Hound audio architecture

When debugging audio problems with HelenOS HD Audio driver in VirtualBox, I noticed that HD Audio driver does not actually report the rates/formats supported by the audio device, nor does it set them. So I tried to implement it. Soon I ran into problems (Hound crashing), but mainly the audio device interface is not up to the task. It just expects the audio device to be something like a Sound Blaster, basically being able to set any rate from a (min, max) interval. (In reality, SB can only set the rate approximately.

Also note that I found that we round the rates to multiples of 100 Hz when communicating to Hound. Oh my. In the end I found out that Hound never sets any other format than the default 44100Hz / stereo / 16-bit, because it starts playing even before any stream is started, so it has no way of knowing what format to set.

So I'm not sure if it even makes sense to improve the driver within the scope of the current audio framework, which is severely limited. Even while developing the HD Audio driver I realized that it's a poor match for HelenOS audio architecture. Here's a compiled list of problems encountered so far:

• Each sound card / audio device can only have up to one input and one output (HD Audio can have mutiple).
• Both input and output must support the same rates/formats (can be different in HD Audio).
• Audio device is expected to support basically any rate in some (min, max) interval (but HD Audio only supports a short list of specific rates).
• Rate is passed from client to server in multiples of 100 Hz.
• Audio playback starts as soon as client connects, even if no streams are playing. This means we don't know what the format will be, so we pick default format (and we cannot convert rates).
• Everything thus plays at 44100Hz / 16 bits / stereo.

Clearly the audio architecture needs a lot of (re)work. Complete rework. Yup. (Not today, though).

File Dialogs - Deluxe!

As you might know, our temporary file dialogs were previously a poor man's affair, containing just a plain text entry and an OK / Cancel button pair.

But now lo and behold!

A file list entry for browsing files/directories complete with a scrollbar. And, as is the standard for libui, both in graphics and glorious text mode. Is that cool or is it not? Granted, it's not perfect, but I can feel progress is being made...

And I can assure you it's only going to get more exciting. Just wait and see.

All that is necessary for the triumph of evil is that good men do nothing.

Helen's Weekend Out

Helen decided that, due to lack of snow and abundance of sunshine, she'd love to spend the weekend hiking in the mountains. Here's the postcard she sent:

I love this 'speedpainting' by David Revoy (CC BY 4.0). Here's a lik to the full size image and to his original blog post.

Come, Mindy!

Here's another "meme". As you should already all know, I love making jokes that nobody ever gets (except for myself). Ha Ha.

Brain: Come, Mindy, it's time for us to write an optimizing C compiler for the Z80 from scratch!
Mindy: Why?
Brain: Writing an LLVM backend is a daunting task.
Mindy: Why?
Brain: It's big, complicated, and a moving target.
Mindy: Why?
Brain: Because it's something I want to do!
Mindy: Okay, I love you!

And here's the original text: (in case you haven't watched all the episodes of Animaniacs)

Brain: Come, Mindy, it's time for us to take over the world!
Mindy: Why?
Brain: By right of superior intelligence I am best suited to guide the destiny of this planet.
Mindy: Why?
Brain: My impairable powers give me the mandate.
Mindy: Why?
Brain: Because it's something I want to do!
Mindy: Okay, I love you!

Sport need no grammah

If your ah sportn persn ya dun nead ta lern na stinkn gramah.

Also, if you don't speak Czech you probably won't get this.

HelenOS 0.11.2 is out. What's new?

HelenOS 0.11.2 was released on Friday, December 17th. I also posted a screencast highlighting the new features, like the new HiKey960 port, Navigator file manager, UI and text mode improvements.

Some things didn't make it in, like mouse support in EGA console, Unicode support in serial console. I also forgot to show Calculator and Hello running in text mode.

It felt really good to get this release out of the door. And now, back to work!

Skywatching & my very first astrophotograph

Enjoyed some sky watching with the kids in the evening. Good conditions to spot Venus, Jupiter, Saturn & the Moon. Took out my old small refractor and attempted the very first atrophotograph in my life. I had no idea what I was doing, thought I had to remove the eye piece. After putting it back, here's the result (or rather the best of several attempts).

Considering I was just desperately trying to hold my mobile phone camera next to the eypiece, and using a crappy 20-year-old telescope, and considering a mild haze, the results are pretty stunning, don't you think? Well, at least I am stunned ^_^. For your convenience, I mirrored the image back to the right orientation (since the refractor is mirroring the image).

Doodle quiz

By the horrible power that be my miserable doodling skills, I present you this quiz. Here's a 'cartoon' (I really have no choice but use quotes) commenting on current happenings in the microkernel OS world:

Can you describe what is happening in the scene? If you can, than you're really really good.