bare metal

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 computer. Real

bare-metal programming involves things like building bootPROMs 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

computer 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, especially tricks for speed

and space optimisation that rely on crocks such as overlapping

instructions (or, as in the famous case described in TheStory of Mel, interleaving of opcodes on a magnetic drum to

minimise 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 computer 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 RealProgrammer.

In the world of personal computing, bare metal programming is

often considered a Good Thing, or at least a necessary evil

(because these computers 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 computer 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.

[Jargon File]