Bought to use inner parts to complete the Powerbook 540. Now in pieces with no frame to connect screen to base. Color screen has some damage and some incorrect vertical lines.

The PowerBook 520 series introduced the built-in trackpad to personal computers — a feature so fundamental to laptop design that it has appeared on every notebook computer since. The 520 and 520c used 68LC040 processors and the new PB5xx form factor that moved the trackpad below the keyboard, giving users a more natural pointing experience than the old center-mounted trackball.

• EveryMac