bare metal n.
1. [common] 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
(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.