Language that system calls are implemented in Lately, I have been reading about operating systems design.  The idea that all user space programs utilize Kernel services via a "System Call Interface" have got me thinking further into this.

Is system call implemented in specific language like C/C++ on each operating system or it is some sort of assembly language or machine code?
System calls are usually implemented in C (or at least that used to be the case) mixed with assembly language. That said, everything gets translated eventually to machine code.