command. Runs the garbage collector, reclaiming unused nodes. Logo does this when necessary anyway, but you may want to use this command to control exactly when Logo does it. In particular, the numbers output by the Nodes operation will not be very meaningful unless garbage has been collected. Another reason to use GC is that a garbage collection takes a noticeable fraction of a second, and you may want to schedule collections for times before or after some time-critical animation. If invoked with an input (of any value), GC runs a full garbage collection, including GCTWA (Garbage Collect Truly Worthless Atoms, which means that it removes from Logo's memory words that used to be procedure or variable names but aren't any more); without an input, GC does a generational garbage collection, which means that only recently created nodes are examined (The latter is usually good enough).
Release Notes for Version 4.64(2), Frame, FrameEnable, FrameSetBackgroundColor, FrameSetClientSize, FrameSetFontName, FrameSetFontSize, FrameSetFontStyle, FrameSetFontWeight, FrameSetShape, FrameSetSizer, Nodes, Release Notes for Version 4.685