All The Weyrs of Pern is a novel written by author Anne Mccaffrey and published in 1991. Set in her Dragonriders of Pern universe, AtWoP is an excellent addition to the series.
The people of Pern discover the remains of the first town established on the planet, Landing, and with it a link to their forgotten past. As they clear the debris from the buildings, solar panels are revealed, feeding power to AIVAS - the Artificial Intelligence Voice Address System. This massive store of knowledge gives the Pernese the chance to rid themselves of their ancient and deadly enemy - Thread.
I enjoyed All The Weyrs of Pern very much because it shows how well the worlds of fantasy and sci-fi can be blended together - mile-long spaceships and graceful dragons co-existing perfectly. This book should appeal to anyone who enjoys fantasy or science fiction, but the other, more fantasy oriented novels in the sequence should be read first.