My real-time operating system

http://ericw.ca/blog/posts/my-real-time-os/

by eworoshow • 18 years ago

44 26 18 years ago

eworoshow8• 18 years ago

I wrote a toy operating system for school that I recently(ish) released to the world. It comes with source code and design documents so I thought it might be interesting for people to poke around in.

kragen4• 18 years ago

Looks like fun! What kind of drivers does it have? And what license?

eworoshow8• 18 years ago

It was fun! Well, fun modulo writing and debugging all the code in three months.

As for drivers, the OS really only interfaces with 8250 UARTs; both the VT100 terminal and the Marklin digital interface for the trains were connected via RS-232 serial ports. There is also, embedded in the kernel, a micro VGA driver for displaying debug messages.

I don't exactly have a specific open source license in mind. Right now I suppose you could say it's public domain. I'd be happy for it to stay that way, unless somebody would like to convince me otherwise?

holdenk• 18 years ago

CS452 for the :P I hear rumours they are moving away from x86 for that course, have you heard anything about it?

eworoshow8• 18 years ago

Yes, Cowan wants to buy ARM processors. I believe he is planning on soliciting funding from the Mathematics Endowment Fund this term. (disclosure: I'm the MEF Director)

s3graham2• 18 years ago

Ah, that video brings back nice memories of bleary-eyed nights in the Real-Time lab. :)

... That and rage at the crappy, broken, unreliable sensors we had at the time. Damn hardware always messing with pretty software abstractions.

What was your gratuitous fluff process to "prove" that the OS was mostly real-time-ish?

eworoshow8• 18 years ago

Demonstrating that the OS was real-ish time consisted of showing that (1) it never dynamically allocates memory, (2) it uses constant-time algorithms. More practically I did a bunch of timing to show that, under real loads, it generated responses under certain (arbitrary) thresholds. In conclusion: a process lacking even the smoke and mirrors of rigor.

s3graham2• 18 years ago

Sorry, I didn't mean to imply your measuring process was fluff.

When I did 452 we had to do something on-screen, to demonstrate responsiveness. I did the "water demo effect" (similar to http://www.derschmale.com/demo/pixelbender-water/PixelBender...). It had to animate without hitching under load, which I guess correlates with your response timing tests (the arbitrary threshold being 60 or 30 Hz in this case).

Anyhoo, I meant "process" in terms of OS-level process, and "fluff", because mine was just lame graphical fluff. :)

btw, planning any more co-op terms before you graduate? Drop me a line.

tlrobinson• 18 years ago

Wow, model trains have gotten fancy! (http://www.marklin.com/CentralStation08.pdf)

The one I had as a kid looked like this: http://www.rubylane.com/shops/seniormovingspecialists/item/T... (though it was previously my dad's)

DanielBMarkham3• 18 years ago

Wow!

The only thing I can think of as a next step is to install micro-webcams in the engines and have that virtual-world headgear to see the scenery from the model's viewpoint.

Amazing!

eru3• 18 years ago

Startup oppurtunity?

By the way: Why are model railroads still expensive? Shouldn't the Japanese or Koreans (etc) have invaded the market by now with affordable, high-quality goods?

My real-time operating system

Related Stories