User`s guide

ASSIGN
3. The following example is typical for a system that uses a dual-drive diskette
device. Several users can share the same system software on DY0 and maintain
their own data files on diskettes that they run in drive 1. When you use
the following command, references to files without an explicit device name
automatically access DY1.
.ASSIGN DY1: DK:
RT–11 Command Descriptions 5