@AmenZwa @ambihelical The various flavors of BSD are still used on servers, although obviously desktop installations are few even compared with Linux.

There are a number of real time operating systems still in heavy use. Windows, MacOS, and Linux are all Not Suitable for real time.

A certain real time guy told me about a certain new international airport whose opening was delayed 18months because some idiot sold them on using Windows to control the automated baggage handling. Luggage would go down a very long conveyer that had switches to dump things off at all the intermediate dropoffs for arrivals or departures, but because Windows is not real time, the process handling the switches had random delays (Gaussian distribution) and luggage kept getting transported to the end of the line.

So they had to scrap that and delay opening the airport until they could replace Windows with an RTOS (and port that related apps).

I've never seen this story online, but I trust the guy who told me, and its obviously something that illustrates well why sometimes you *have* to use an RTOS.

@dougmerritt @ambihelical You're quite right about BSD. Many servers run BSD: I heard that Heroku runs on FreeBSD, but I could be off here. Also, SONY PlayStation runs on a fork of BSD, and tonnes of appliances too—probably NetBSD variants. I wouldn't be surprised if many modern hard and soft real-time embedded OSs were modelled after BSD, if not outright derived therefrom. But in terms of installed numbers, Windblows blows everything else away. Sad.

I know a team that is implementing a multi-sensor, multi-target tracking system using Windows running on a handful of laptops, stitched together with a bloated microservices and the system is being implemented in TypeScript and C#. Since I know the senior engineers, I asked them why they're not using FreeRTOS, VxWorks, QNX, or some RTOS. They told me that none of them has ever heard of "RTOS". Bless their little hearts.

@AmenZwa @ambihelical Wow, that EDDB fiasco is just unbelievably bad! They didn't mention corruption, but that is the typical reason that megaprojects end up being screwed up in 100 ways, not just 1 or 2.

Hmm, are you a pilot? You seem like the over-achiever type. :) My Berkeley friend Bob Toxen (co-author on that article I pointed you to) has been a pilot for ages; The actual name of his consulting service: "Fly By Day Consulting". That punning is right up there with Rich Morin's home basement Sparc server room for his business "Canta Forda Labs" (I didn't get it until someone said it out loud).

Your surmise about it being KDEN is correct. I'm not under NDA, the guy just asked me not to mention his name (*he* was probably under NDA), but I figure that so long as I don't have a confirming source to cite, I may as well keep the story vague.

> I wouldn't be surprised if many modern hard and soft real-time embedded OSs were modelled after BSD, if not outright derived therefrom

Not that I know of. The most heavily used ones have been in development since before the *nix software architecture was the clear winner. At least one of them retrofitted a Unix-compatible API & user environment around their older non-*nix kernel . I did semiconductor manufactoring process control under LynxOS -- pretty nice.

There are configurations of Linux (RTLinux, Real-time Linux) that support soft real time features, but alas that's not in the mainstream kernels.

(Seems to me that these days, the full featured OSes like Linux and BSD *should* all have real time schedulers and related features in their mainstream, and should be hypervisor-ish, etc.)

Of interest: https://en.wikipedia.org/wiki/Comparison_of_real-time_operating_systems

@dougmerritt @ambihelical Yeah, EDDB and KDEN are quite a mess. The Pentium floating-point bug comes close in the tech sector.

I used to fly the Bell 47 in my youth, and I never progressed beyond the low hours. I've not been in a cockpit for decades. Flying, like engineering and programming, is sustainable only if it is practised obsessively. One either must fly regularly, at least a few hours a month, or opt to become a commercial pilot. Otherwise, that license is a license to kill oneself. So, when I got into engineering, I decided to give it up.

"Fly By Day Consulting", "Canta Ford Labs", "TriloBYTE", "Acorn"—we used to have creative and evocative names in IT. Even the logos were fanciful, like SUN, SGI, NeXT. Today, we have made-up words and bland logos.

I use FreeRTOS these days, mostly with the STM32 family. I've only heard of LynxOS, but I've never used it. I shall have to look into it; thanks, mate.

I strongly believe that every successful OS family should officially establish different branches within itself for high-performance, batch-processing, server, desktop, handheld, and embedded. And each branch should offer a few different schedulers. This would be preferable to the current scenario, where the individual groups roll their own customised versions.