Well, it’s turtles all the way down. [1] Even the assembly language programmer is running on top of the OS. The OS is deep magic: runtime interrupts happening

Well, it’s turtles all the way down. [1] Even the assembly language programmer is running on top of the OS. The OS is deep magic: runtime interrupts happening to make the floating point hardware handle certain edge cases correctly. Fork system calls that semantically provide a copy of the parent’s address space in almost no time by using virtual memory tricks (copy on write pages). Virtual memory itself. The OS lets the user space assembly language programmer touch some of the hardware directly, but not all of it. [1] https://en.m.wikipedia.org/wiki/Turtles_all_the_way_down https://en.m.wikipedia.org/wiki/Turtles_all_the_way_down