SNAX Connection Manager (SNAX/CM) Manual

Glossary
097842 Tandem Computers Incorporated Glossary–5
OBEY file. See command (OBEY) file.
object. In Tandem terminology, an object is an entity that can be configured,
controlled, and inquired about by the operator.
packet-switching data network. A network that uses packet switching as a means of
transmitting data.
Passthrough. A function of the SNAX/XF line access software that allows a 3270
terminal attached to a Tandem system to switch between Tandem and IBM
applications. Passthrough lets a host application program communicate with SNA
devices connected to a Tandem system as though the devices were connected to a
cluster controller.
PDN. Public data network.
physical connection. The media (hardware and software) through which data is passed
between origin and destination subareas. Physical connections between a host
processor and a communication controller in an SNA network can be made by either
an SDLC link or a channel attachment.
physical layer. Layer 1 in the OSI Reference Model. This layer establishes the actual
physical connection between the network and the computer equipment. Protocols at
the physical layer include rules for the transmission of bits across the physical medium
and rules for connectors and wiring.
physical unit (PU). That part of a device (hardware or software) that provides control
functions for its own node and for the other less intelligent device nodes attached to
the PU. Every device or logical unit in an SNA network is associated with a physical
unit.
port. A port is a unique name used by SNAX/CM to identify and access a particular
TLAM I/O process for Token-Ring networks or an X25AM line handler subdevice for
X.25 networks. Up to 254 ports can be configured in a SYSGEN operation; SNAX/CM
controls each port independently and supports the connection of one switched PU for
each port.
primary station. (1) The station that at any given instant has the right to select and to
transmit information to a secondary station, and the responsibility to ensure
information transfer. There should be only one primary station on a data link at one
time. (2) A station that has control of a data link at a given instant. The assignment of
primary status to a given station is temporary and is governed by standardized control
procedures. Primary status is normally conferred upon a station so that it may
transmit a message, but a station need not have a message to be nominated primary
station.
process. A unique execution of a program. The operating system is a collection of
processes cooperating by using a common message system.
protocol. A formal set of rules governing the format, timing, sequencing, and error
control of exchanged messages on a data network.
programmatic interface. A means for a program to communicate with another program.