For 50 years I was a software/systems engineer engaged in cold bare metal hard real time full stack embedded systems.
Originally posted by gatorguy This has the right feel to it. We know that Pentax uses the Socionext Milbeaut image processing system on a chip (SOC), which contains a set of quad-core ARM CORTEX core processors along with a small DSP (digital signal processor) array. We also know that Pentax embraces reuse, essentially reusing the common system guts across their processor lines - crop, full-frame, medium frame, and this can be extended to their 360 degree cameras.
As soon as the Milbeaut processors support a new capability/functionality Pentax supports it usually enhancing the basic capability.
Also as gatorguy posted the eSOL’s Real-time OS supports the ARM processor architecture. eSOL has major client support - so they are not a fly by night shop.
.... and Socionext is a major partner of eSOL, so the entire vertical integration is there. That provides enormous risk mitigation for Pentax, along with a source of accelerating the entire development process.
Originally posted by Lord Lucan If it is modified Linux, wouldn't the camera maker have to provide a publically available version of their source code?
Usually - however, there are so many distributions and specialized forks of Linux, some of which only used the original Linux code as a blueprint - essentially rewriting the actual code so as to be original works.
Originally posted by ProfessorBuzz There is a very large world of ARM OSs available, some original, others using a "Linux template". The company that I retired from has its own ARM-based OS that provides for specialized cyber security capabilities - essentially a fully customized secure separation kernel - based on formal methods.
Originally posted by Bob 256 A camera doesn't necessarily have to have an "operating system". For example, what operating system does an Arduino or Raspberry Pi use? They actually "operate" using machine code appropriate for each micro-controller or micro-processor, although the actual code might be written using a compiler like C+, but the actual "operating system" doesn't exist in a standardized form such as Windows, MacOS, Android, or the like. Most cameras probably operate using a "proprietary" operating system written in machine code, and there could be many, many variations on such, being different with model and maker (even within sub-models if a controller is swapped out for a more capable chip).
The Pi uses the Raspberry Pi OS (previously called Raspbian) which is a derivative/tailored version of Linux. Due to the nature of the Pi's hardware, and its user base, they really needed an off-the-shelf OS version tailored for the bare hardware board that was selling. Without the software support, the Pi would have not been as successful as it has been. Having a fully rolled functional OS based on Linux with known interfaces provided the full package to make the product successful. The same goes for the Arduino to a somewhat lesser extent
Pentax is unable to afford a custom OS written in assembly (and the maintenance would be financial suicide). Actually, today - the optimizing compilers are so good, that there is little need for custom assembly language outside of potentially a few specialized areas. As noted above where real-time OS that is tailored to the hardware (both ARM and the specific image processing SOC), there is no need, Pentax has (apparently) essentially just able to purchase it off the shelf. The eSOL's OS even supports the DSPs in the SOC.
That leaves Pentax to focus on what they do best - add their tailoring and customizations to the overall product. The main problem that Pentax has is that in using these off-the-shelf subsystems - they are at the mercy of the basic thruput of the Milbeaut SOC, which determines their overall FPS for the particular sensor they are using. Nikon uses the same Milbeaut SOC apparently with a lot of custom-tailoring. What I find somewhat interesting is that Ricoh and Pentax do not use the same image processing SOC.