Dictionary.net

The tendency of manufacturers (or, byextension, other designers) to come up with products thatdon't fit with the old stuff, thereby making you buy eitherall new stuff or expensive interface devices.The term probably came into prominence with the appearance ofthe DEC KL-10, none of whose connectors matched anythingelse. The KL-10 Massbus connector was actually *patented*by DEC, who reputedly refused to licence the design, thuseffectively locking out competition for the lucrative Massbusperipherals market. This policy was a source of frustrationfor the owners of dying, obsolescent disk and tape drives.A related phenomenon is the invention of new screw heads sothat only Designated Persons, possessing the magicscrewdrivers, can remove covers and make repairs or installoptions. Older Apple Macintoshes took this one stepfurther, requiring not only a hex wrench but a specialisedcase-cracking tool to open the box.With the advent of more open-systems computing this term hasfallen somewhat into disuse.Compare backward combatability.