This is the Fifth iteration of the "Apple Service Technical Procedures" series. In this guide Floppy drives are mainly discussed. Everything from how to repair, troubleshoot, and upgrade the Disk II, Disk ///, ProFile, DuoDisk, Disk IIc, UniDisk 3.5 (800k External Drive), and Apple 5.25 Drive/5.25 UniDisk is described in vivid detail with many illustrations, testing solutions, chip ID's, diagrams, and part numbers. I added section labels to better see or find what you are looking for.