bare metal

noun2

1. •
   A runtime environment where little to no abstraction is available: usually employing a low-level programming language, without access to any operating system facilities, and interfacing hardware directly.

   • Real programmers don't write applications programs; they program right down to the bare metal. Applications programming is for wimps who can't do systems programming. — 1987
2. •
   Physical hardware, as opposed to virtualised.

   • In 1998 virtualization was "rediscovered" for the x86 platform by VMWare, but due to instruction translation the approach taken was slow when compared to bare metal performance. — 2009