Troubleshooting Terminal, Printer, and Serial Device Connections - Edition 5 (32022-90058)

Glossary
DDX
Glossary
116116
transmission circuit. Synonyms: data
communications equipment, dataset. A modem is an
example of a DCE.
DDX The national public PSN of Japan.
DDFA DTC Device File Access Utilities. A set of
HP-UX utilities which is used by systems and user
written applications to programmatically access
devices attached to DTC ports.
DDP Direct Distribution Panel; a distribution panel
that serves as the electrical and physical interface
between a DTC 72MX mux board (asynchronous
processor board) and up to eight asynchronous
devices for direct connections. See MDP for modem
connections.
dedicated printer A printer that can be used only
by one host on the LAN — the one specified in the
Destination Node Name in that printer’s
configuration screen.
demodulation The process by which the
information-bearing signal is retrieved from a
modulated carrier wave. The inverse of modulation.
destination node name In DTS configuration, it is
either 1) the name of a host that a user can be
connected to by default (if switching is not enabled
for that user, or if automatic modem connection is
enabled), or 2) the name of the only host that can
access a dedicated printer.
device class A collection of devices that have some
user-defined relation. Device classes are assigned
through use of the NMMGR configuration program.
device-dependent characteristic A file
specification for which modifications are restricted
because of the type of device on which the file is
opened. For example, data directed to terminals
must have a blocking factor of one.
device driver A software module that controls a
specific type of input/output device.
devicefile A file being input to or output from any
peripheral device except a disc. MPE/iX allows
operations to be performed on the device itself as if it
were a file.
device independence A characteristic of the
operating system that allows users to selectively
redirect input/output from a program, session, or job
without regard to the nature of the device.
device name See PAD name.
Dial ID protocol A proprietary Hewlett-Packard
protocol that provides security checking and address
exchange for dial links.
dial link A connection made through public
telephone lines.
direct-connect device An asynchronous device
that is connected directly to a DTC through an
RS-232-C or RS-422 cable, with no intervening
communications equipment. Also referred to as a
“local connection.”
direct connection A leased line, private line, or
other non-switched link in a network.
direct dial A dial link through which only one
remote node can be reached.
direct-path branching The process of directly
accessing any screen in NMMGR by entering a path
name in the Command: field. The path name must be
preceded by an at sign (@).
download The process of loading operating code
and configuration files into the DTC’s memory. The
DTC is downloaded by the MPE/iX host for LANs
using host-based network management, and by the
PC for DTCs managed by the OpenView DTC
Manager.
driver Software that controls input/output devices
including NS 3000/iX links.
DTC Datacommunications and Terminal Controller.
The DTC is a hardware device, configured as a node
on a LAN, that enables asynchronous devices to
access HP 3000 Series 900 computers. Terminals can
either be directly connected to the DTC, or they can
be remotely connected through a Packet Assembler
Disassembler (PAD). The DTC can be configured
with DTC/X.25 Network Access cards and DTC/X.25
Network Access software. A DTC/X.25 iX Network
Link consists of two software modules: the X.25 iX
System Access software (running on the host) and
the DTC/X.25 Network Access software (running on
the DTC).