BSD Real-Time Operating System NuttX Makes Its 100th Release: NuttX 6.33

paugq writes "NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 32-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOS's (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments. NuttX was first released in 2007 by Gregory Nutt under the permissive BSD license, and today the 100th release was made: NuttX 6.33. Supported platforms include ARM, Atmel AVR, x86, Z80 and others."

Re:Ambitious

[OzPeter]

Seems like a pretty ambitious project to run on a Z80. Good thing this isn't April 1st.

Git off my lawn you young whippersnapper.

I was running OS-9 [wikipedia.org] on a Tandy Colour Computer (6809E, 2MHz) back in the late '80s. A full preemptive multi-tasking multi-user unix like system in a tiny little box. I even had a GUI running on it (well for about 1/2 an hour as it was too frisking slow!). Its amazing what you can do if you avoid bloat.

Re:What makes an OS realtime?

[cold fjord]

What is Real Time and Why Do I Need It? [qnx.com]

Re:What makes an OS realtime?

[tiagosousa]

Had a friend ask me this once. I honestly couldn't come up with an answer. You look at the nuts and bolts of O/S's both realtime and non realtime, and it's basically all the same stuff, with more emphasis given to lower transaction times. Is it just a buzzword? Not trying to troll, but if someone has a definitive answer I'd love to hear it.

Realtime simply means that certain operations are guaranteed to complete in a given timeframe. This is harder than it appears.

Re:What makes an OS realtime?

[elfprince13]

Did you bother looking it up?

A real-time operating system (RTOS) is an operating system (OS) intended to serve real-time application requests. It must be able to process data as it comes in, typically without buffering delays. Processing time requirements (including any OS delay) are measured in tenths of seconds or shorter. A key characteristic of an RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is jitter.[1] A hard real-time operating system has less jitter than a soft real-time operating system. The chief design goal is not high throughput, but rather a guarantee of a soft or hard performance category. An RTOS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a deadline deterministically it is a hard real-time OS.[2] An RTOS has an advanced algorithm for scheduling. Scheduler flexibility enables a wider, computer-system orchestration of process priorities, but a real-time OS is more frequently dedicated to a narrow set of applications. Key factors in a real-time OS are minimal interrupt latency and minimal thread switching latency; a real-time OS is valued more for how quickly or how predictably it can respond than for the amount of work it can perform in a given period of time.[3]

Re:What makes an OS realtime?

[EMG at MU]

A hard real time system has to be deterministic. Operations have to happen exactly at the right times, and take exactly the same amount of time every time. Nothing can go on inside the OS that could delay or slow down the vital operations of the embedded device.
That being said you can have a real time os and do things that will make your system not deterministic. Unless specially designed (ethercat ect...), filesystems and network communication are typically non deterministic.

I suppose another thing I associate with real time is concept of a watch-dog. If you have a task that monitors some A2D and it absolutely has to run every 10ms in order for the system to function properly, you want your watch-dog to trip if your task doesn't run within some window.

This isn't BSD!

[l2718]

The headline creates the impression that this is a real-time adaptation of BSD (the "Berkeley Software Distribution", that is, BSD Unix). In fact, this OS is an original development; it is merely licensed under the terms that BSD is licensed under.

Would the headline have said "A GNU real-time OS" if it was licensed under the GPL, the license of the GNU operating system?