bare metal

bare metal n.  1. New computer hardware, unadorned with such
   snares and delusions as an {operating system}, an {HLL}, or
   even assembler.  Commonly used in the phrase `programming on the
   bare metal', which refers to the arduous work of {bit bashing}
   needed to create these basic tools for a new machine.  Real
   bare-metal programming involves things like building boot proms and
   BIOS chips, implementing basic monitors used to test device
   drivers, and writing the assemblers that will be used to write the
   compiler back ends that will give the new machine a real
   development environment.  2. `Programming on the bare metal' is
   also used to describe a style of {hand-hacking} that relies on
   bit-level peculiarities of a particular hardware design, esp.
   tricks for speed and space optimization that rely on crocks such as
   overlapping instructions (or, as in the famous case described in
   {The Story of Mel, a Real Programmer} (in Appendix A),
   interleaving of opcodes on a magnetic drum to minimize fetch delays
   due to the device's rotational latency).  This sort of thing has
   become less common as the relative costs of programming time and
   machine resources have changed, but is still found in heavily
   constrained environments such as industrial embedded systems, and
   in the code of hackers who just can't let go of that low-level
   control.  See {Real Programmer}.

   In the world of personal computing, bare metal programming
   (especially in sense 1 but sometimes also in sense 2) is often
   considered a {Good Thing}, or at least a necessary evil
   (because these machines have often been sufficiently slow and
   poorly designed to make it necessary; see {ill-behaved}).
   There, the term usually refers to bypassing the BIOS or OS
   interface and writing the application to directly access device
   registers and machine addresses.  "To get 19.2 kilobaud on the
   serial port, you need to get down to the bare metal."  People who
   can do this sort of thing well are held in high regard.