SNAX/HLS Diagnosis and Support Manual

Glossary
Glossary–6 104706 Tandem Computers Incorporated
PERIPHERALS paragraph. A paragraph within the SYSGEN configuration file that is
used to define the SNAX/XF $SSCP process (Service Manager) and the SNAX/XF
lines.
physical unit. 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.
pipelining. A session is pipelined if it can be accessed by more than one requester. Even
though pipelined sessions can be accessed by more than one requester, there is still
only one read work queue and one receive data queue for the session. These queues
are shared by the requesters.
PIU. Path information unit.
PLU. See primary logical unit.
primary logical unit (PLU). The logical unit that controls a LU-LU session. Within each
LU-LU session, one of the LUs is the primary and the other is the secondary. The most
important control that the PLU exerts is the formatting and sending of the BIND
request that initiates the session.
process. A unique execution of a program. The Tandem NonStop Kernel is a collection
of processes cooperating by using a common message system.
process pair. Two processes: a primary process that is active, and a secondary, backup
process in another CPU that is ready to take over if the primary process fails.
protocol. The set of rules governing the operation of communicating entities.
PRT protocol. One of the SNAX/XF high-level 3270 protocols. The PRT protocol
supports line-at-a-time communication with certain SNA 3270 type printers. The
calling process sends text; SNA adds any necessary printer control characters to the
outgoing text. See also CRT protocol and interactive terminal interface (ITI) protocol.
PSDN. Packet-switched data network.
PVC. Permanent virtual circuit.
QLLC. Qualified Logical-Link Control protocol.
RDT. Resource Definition Table. The RDT is the standard input file to the SNAX/HLS
process. It contains PROFILE, INIT-SELF, and BIND records. It is the configuration
database of the SNAX/HLS process.
remote passthrough. Any passthrough session that spans two or more Tandem nodes.
SCF. See subsystem control facility.
SDLC. Synchronous data link control.
SDT. Start data traffic request.
secondary logical unit (SLU). One of the two LUs involved in a LU-LU session. The SLU
functions under the control of the remote PLU. It accepts an incoming BIND request
from the PLU.