5.25" Ext Drive Adapter.  (360 and 1.2MB versions)
4869 Ext Floppy 
General Floppy Info
Drive Pinouts
Data Migration Facility
Mountain Mach-2 Tape Controller (Mach2 Compression))
DASDDRVR.SYS What is it and do you need it?

Repairing the 1.44MB Drive (by Al Savage)

Programming Floppy Disk Controllers
Intel FDCs
   82077  290166.pdf
   82078 44 pin  29047403.PDF
   82078 64 pin  29047504.PDF
National Semiconductor
   PC8477
NEC
   PD765
   PD72065