Apple PowerBook (Duo 270C) - Manual (Page 268)

2. Connect the floppy adapter to the PowerBook Duo.
You hear a click when the adapter is attached.
3. Connect the floppy disk drive’s cable to the floppy disk
drive port on the adapter. The port is marked with this
icon: H
Use only the Macintosh HDI-20 External 1.4 MB Floppy Disk
Drive with your PowerBook Duo. Other disk drives draw more
power than is recommended, and their connectors are of a
different type.
252 Chapter 13: Building a PowerBook Duo System