Xyzzy (computing)

Xyzzy is a magic word from the Colossal Cave Adventure computer game. In computing, the word is sometimes used as a metasyntactic variable or as a video game cheat code, the canonical "magic word".

Modern usage is primarily from one of the earliest computer games, Colossal Cave Adventure, in which the idea is to explore an underground cave with many rooms, collecting the treasures found there. By typing "xyzzy" at the appropriate time, the player could move instantly between two otherwise distant points. As Colossal Cave Adventure was both the first adventure game and the first interactive fiction, hundreds of later interactive fiction games included responses to the command "xyzzy" in tribute.

The origin of the word "xyzzy" has been the subject of debate. According to Rick Adams, the sequence of letters "XYZZY" has been used as a mnemonic to remember the process for computing cross products.Crowther, author of Colossal Cave Adventure, states that he was unaware of the mnemonic, and that he "made it up from whole cloth" when writing the game.

Xyzzy has been implemented as an undocumented no-op command on several operating systems; in Data General's AOS, for example, it would typically respond "Nothing happens", just as the game did if the magic was invoked at the wrong spot or before a player had performed the action that enabled the word. The 32-bit version, AOS/VS, would respond "Twice as much happens". On several computer systems from Sun Microsystems, the command "xyzzy" is used to enter the interactive shell of the u-boot bootloader. Early versions of Zenith Z-DOS (a re-branded variant of MS-DOS 1.25) had the command "xyzzy" which took a parameter of "on" or "off". Xyzzy by itself would print the status of the last "xyzzy on" or "xyzzy off" command.

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