Small Open-Source OSs for Small IoT Devices
A range of open-source operating-system solutions are available for those confined to scaled-down dimensions—homing in on the best option does require some research, though.
Linux has become the de facto open-source operating system (OS), although there are niche alternatives like flavors of BSD (Berkeley Software Distribution). A variety of incarnations target minimal memory platforms such as Ubuntu Core/Snappy and Android Things.
Many commercial open-source solutions are available in this space, too, but they all require virtual memory-management-unit (MMU) hardware.
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