Editing Macintosh Toolbox (section)

{{Short description|System routines for Classic Mac OS}}
The '''Macintosh Toolbox''' implements many of the high-level features of the [[Classic Mac OS]], including a set of [[application programming interface]]s for software development on the platform. The Toolbox consists of a number of "managers," software components such as [[QuickDraw]], responsible for drawing onscreen graphics, and the Menu Manager, which maintain data structures describing the menu bar. As the [[Macintosh_128K|original Macintosh]] was designed without [[virtual memory]] or [[memory protection]], it was important to classify code according to when it should be loaded into memory or kept on disk, and how it should be accessed. The Toolbox consists of subroutines essential enough to be permanently kept in memory and accessible by a two-byte [[instruction set|machine instruction]]; however it excludes core "kernel" functionality such as [[memory management]] and the [[file system]]. Note that the Toolbox does not ''draw'' the menu onscreen: menus were designed to have a customizable appearance, so the drawing code was stored in a [[resource fork|resource]], which could be on a disk.