Complex sentence: A wristwatch was the first wait cursor in early versions of Mac OS. Apple's HyperCard first popularized animated cursors, including a black and white spinning quartered beach ball which could be advanced by repeated HyperTalk invocations of "set cursor to busy".
Split into simpler sentences: A wristwatch was the first wait cursor in early versions of Mac OS. Apple's HyperCard first popularized animated cursors, including a black and white spinning quartered circle resembling a beach ball. The cursors could be advanced by repeated HyperTalk invocations of "set cursor to busy".