User`s guide

Chapter 3

Using Files, Volumes, and Devices

Most DCL commands work with ﬁles stored on volumes in devices. The following

sections summarize information you should know when dealing with ﬁles, volumes,

and devices. See the Introduction to RT–11 for further information.

Using Storage Devices

Files are located on volumes in storage devices. When you issue a command affecting

a previously created ﬁle, RT–11 has to ﬁrst ﬁnd that ﬁle on a volume. If you do not

specify which volume, RT–11 presumes the speciﬁed ﬁle is on the default storage

volume. Otherwise, you have to specify which volume your ﬁle is on.

You specify a volume by specifying the device the volume is in. You do that either by

means of a standard one- or two-character physical-device name or by a logical-device

name.

Specifying Physical-Device Names

If you do not specify a unit number (n) for devices with more than one unit, RT–11

assumes unit 0. If you have SYSGENed your monitor to have extended device-unit

support, you can have more than eight device units.

RT–11 has device names not only for storage devices, printers, and terminals but

also for pseudodevices. These are handler programs of different types that perform

functions similar to real physical devices, such as enabling you to input and output

data in various ways.

Table 3–1 lists the names by which RT–11 speciﬁes real devices (storage devices,

printers, terminals, and so on) and pseudodevices.

Table 3–1: Physical-Device Names

Name Device Speciﬁed

BA: BATCH device handler

DLn: RL01, RL02 disk

DMn: RK06, RK07 disk

DUn: MSCP disk or diskette

DW: RD type disk (Professional 300 series)

DXn: RX01 diskette

Using Files, Volumes, and Devices 3–1