Slang that means "close to the hardware" or deep guts of the system. C's memory management is considered "close to the metal" compared to other application languages because one can easily see and do math on actual hardware RAM addresses (or something pretty close to them).

In general, being CloseToTheMetal sacrifices hardware choice because it can lock the software or item into a particular vendor or equipment model. It may also introduce risk because there is no interface layer to protect one from silly or dangerous ranges, settings, or values. But the upside is often better speed and resource control.

[Note that in EmbeddedSystems this is a complete necessity; embedded folk are always aware of what is going on down at the hardware level to prevent problems from letting the magic smoke out of the little black bug-shaped things.]
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See: BigIron

CategoryJargon