Big iron, as the hacker's dictionary the Jargon File defines it, "refers to large, expensive, ultra-fast computers. It is used generally for number crunching supercomputers such as Crays, but can include more conventional big commercial IBM mainframes".
The term is often used in reference to IBM mainframes, often when discussing their comeback/survival after the assault of lower cost Unix systems. More recently the term is also applied to powerful computer servers and computer ranches, whose steel racks naturally invoke the same association.
The expression may be compared with the slang expression for heavy handguns, derived from the slang "iron" for a handgun ("shooting iron"), as exemplified by the classic country music ballad Big Iron by Marty Robbins about "the ranger with the big iron on his hip".
Famous quotes containing the words big and/or iron:
“You’re not big enough to do this to Rocco! I’ll kill you. You’ll never bring me in! Never!”
—Richard Brooks (1912–1992)
“There is nothing but is related to us, nothing that does not interest us,—kingdom, college, tree, horse, or iron show,—the roots of all things are in man.”
—Ralph Waldo Emerson (1803–1882)