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POSIX.13 Definition of Embedded

Here is the definition and rationale for the term "embedded" as in device or operation system or application code, as used in POSIX.

From: IEEE Std 1003.13-2003, "IEEE Standard for Information

POSIX Realtime and Embedded Application Support". (Later versions of 1003.13 have the same words.)

3.2.7 Embedded Computer System: A computer (and its software) is considered embedded if it is an integral component of a larger system and is used to control and/or directly monitor that system, using special hardware devices.

3.3 Rationale for Definitions (informative) (This clause is not a normative part of IEEE Std 1003.13-2003.)

Embedded Computer System. For the definition of an embedded computer system, the following canonical examples were taken into account:

example, one that uses finite-element methods to predict fluid flow over airplane wings? No. These programs are never considered to be embedded because they are not an integral component of a larger system.

of an embedded system? Yes, regardless of what the disk drive is used for. The software (firmware, actually) within the disk drive controls the HDA (head disk assembly) hardware and is hard realtime as well.

imply that the computer executing the driver is embedded? No, because that computer may be a general-purpose computer that is not part of a larger system.

often say that PDAs are embedded because they are very small and constrained and because PDA OS and application software is kept in non-volatile memory, but PDAs parallel the desktop systems used to run office productivity applications, and no special hardware is being controlled.

Yes. The firmware in the cell phone is controlling the radio hardware.

These radars are ten-story buildings with one to three 100-foot diameter radiating patches on the sloped sides of the building. Yes. These computers were generally some of the most powerful computers available when the system was built, are located in a large computer room occupying almost one whole floor of a building, and may be hundreds of meters away from the radar hardware. However, the software running in these computers controls the radar hardware; therefore, the computers are an integral component of a larger system.

airplane cockpit considered embedded? If the FMS is not connected to the avionics and is used only for logistics computations, a function readily performed on a laptop, then the FMS is clearly not embedded.

embedded? Yes, both in the simulator, and in the thing being tested in the HIL simulator. Hardware is being controlled on both sides.

embedded? Yes. It is part of a larger system, the engine, and it is directly monitoring and controlling the engine through special hardware.

Joe Gwinn

Reply to
Joe Gwinn
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Seems not very useful. They need to define "system" and "special hardware" (which maybe they do and you've merely not included that). Can almost any system be defined arbitrarily large so that everything is embedded? Or small, so that nothing is?

Is every microcontroller embedded, because its CPU system(s) control special hardware devices (GPIO, timers, etc.)? Are those in fact ordinary devices and don't count? But then, wouldn't their examples involve IO or GPIO ports that are just as trivial?

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:

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Reply to
Tim Williams

Just words and definitions. Doesn't seem to actually matter to the real world.

I tend to think of embedded as physically inside some product smaller than a building. But there's no point arguing over in-between cases. Let the Computer Scientists do that; they have lots of time.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Well, the context was the standards world. And the hard-realtime verus soft-realtime folk were fighting tooth and nail about this too.

This definition was accepted because it was way better than what it replaced, and pretty much settled the question - nobody came up with anything better enough to convince the Working Group replace this definition.

Actually, the Computer Science folk don't care about this, and expressed no opinion.

Joe Gwinn

Reply to
Joe Gwinn

It does define these, but it is loose. But it sufficed for the purpose.

The key is intended use, versus physical type.

The whole point of the canonical examples was to in effect define the term by giving the boundaries.

Joe Gwinn

Reply to
Joe Gwinn

Who pays them to do that?

How does this definition affect anything?

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard
Reply to
jlarkin

Whoever pays them to travel to the meetings and to participate. Typically a mix of large companies and the US government.

It shut the argument down, saving much bandwidth. But nothing both technical and important changed.

Joe Gwinn

Reply to
Joe Gwinn

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