It was an operating system in the sense it abstracted much of the hardware into portable syscalls and came with a set of practical utility programs. Really the

It was an operating system in the sense it abstracted much of the hardware into portable syscalls and came with a set of practical utility programs. Really the only assumption hardware had to conform was a certain memory map layout. Process isolation does not make much sense on a 2mhz 8 bit CPU with 64Kb address space anyway. MS DOS didn't do that either, and there are still modern embedded OSes that don't do process isolation.