bolt-on

[T]he first model of this now most famous line of related types, the [Gibson] Les Paul also appeared in 1952, […] The trapeze style tailpiece and combined bar bridge was also fitted, although this gave way to a bolt-on bar bridge by 1953.

This week we take a close look at four top contenders in the multitasking arena […] All the multitasking systems available for microcomputers today fall into one of two distinct categories: "bolt-on" multitaskers, which add multitasking to an operating system (DOS, for example) that originally executed one task at a time; and "built-in" multitaskers, which are part of the operating system by design.