Acronym for Virtual Address eXtension. The VAX was the most successful minicomputer in history, possibly excepting its immediate predecessor the PDP11.

It was released in 1978 and was only recently retired in 2000. (HP/Compaq want you to replace VAX with Alpha.)

It was the Hacker's favourite machne until the advance of the microcomputer (The IBM PC) in about 1986. It is especially noted for its large, assembly code-programmer-friendly instruction set - an asset that became a liability after the RISC revolution.

VAX is also a British brand of carpet cleaner (http://www.vax.co.uk/) whose advertising slogan, "Nothing sucks like a VAX!" became a battle-cry of RISC partisans. It is even sometimes claimed that DEC actually entered a licencing deal that allowed them to market VAX computers in the UK in return for not challenging the carpet cleaner trademark in the US.

Linux has been ported to the VAX (http://linux-vax.sourceforge.net/), and NetBSD runs on it as well, but if you're using a VAX you're probably maintaining a legacy system and it will probably use VMS.

Cool things to do with a VAX include turning it into a bar.