https://atari-wiki.co.uk/index.php?title=WD1770/1772_5_1/4_%22_Floppy_Disk_Controller/Formatter
WD1770/1772 5 1/4 " Floppy Disk Controller/Formatter - Atari Wiki
floppy disk controllerformatteratariwiki
https://stason.org/TULARC/pc/hard-disk-floppy-controllers/E-H/GSI-INC-Two-EIDE-devices-MODEL-18-PART-1533-18-03.html
MODEL 18 (PART #1533-18-03-1 AND EARLIER) Hard Disk/Floppy Controller Settings and Configuration
MODEL 18 (PART #1533-18-03-1 AND EARLIER) hard disk/floppy controller and its configuration, connections, layout, pinout and other specs
hard diskfloppy controllermodelpartearlier