Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

Chapter 2 47
Controlling Asynchronous Devices Programmatically
Device Operation Modes
Slaved Devices
If two devices share the same port in the DTC (one device is connected
to the port and the other device is connected by an additional cable to
the first device), only one device is recognized by the ASC software. The
device that is recognized is referred to as the master device, while the
other device is called a slave of the master. A wide variety of devices
can be connected as slaves, including terminals, printers, card readers,
flexible-disk drives, cartridge tape units and plotters. Slaved devices
are considered programmatic because the device is controlled through
an application. They never accept sessions and are not spooled.