Small resource requirements. RetroBSD needs only 128 kbytes of RAM to be up and running user applications.

Memory protection. Kernel memory is fully protected from user application using hardware mechanisms.

Open functionality. Usually, user application is fixed in Flash memory - but in case of RetroBSD, any number of applications could be placed into SD card, and run as required.

Real multitasking. Standard POSIX API is implemented (fork, exec, wait4 etc).