Introduction to Tandem X.25 Capabilities

Glossary
065307 Tandem Computers Incorporated Glossary–1
This glossary includes a selection of terms used in this manual. Definitions of
communications terms are brief and not very detailed. Many textbooks and technical
dictionaries define these terms in more detail.
3650/6100 Communications Family. The 3650/6100 Communications Family are
programmable controllers, providing multiple protocol support. The product
numbers of the 3650/6100 family controllers supported by X25AM are the 3650 CSS
(6110), the 6100 CSS (6101), the 6105, and the 3605.
ABM. Asynchronous Balanced Mode. A mode of communications within the ADCCP
protocol whereby two combined stations communicate on a point-to-point link.
Either or both stations can issue commands to set up or dissolve the link. During data
transmission, the stations function as peers. This mode is also used by the HDLC
protocol.
access method. An I/O process that allows applications running on a NonStop system
to communicate with other systems or devices. X25AM is an access method for X.25
communications.
address. Unique network designation identifying a device, as described in X.121.
There is also a station address used for the data link layer. There are only two possible
addresses on the data-link layer, 01 and 03, which distinguish between commands and
responses sent by the DTE and the DCE.
ASCII. American Standard Code for Information Interchange. Standard method of
coding data, consisting of seven bits for each character plus one parity bit.
ATP6100. A Tandem product used to connect terminals to Tandem systems.
attribute. In SCF, an attribute is a characteristic that can be specified for an X25AM line
or subdevice. For example, most of the optional network facilities can be specified as
either a line or subdevice attribute, using SCF.
BCUG. Bilateral closed user group. Optional network facility that allows access
restrictions between pairs of DTEs.
binary synchronous communications (BSC). Communications protocol using a standard set
of control characters and control character sequences for synchronous
communications.
bit. Binary digit. Smallest unit of information, represented as a 1 or a 0.
block mode. A type of operation in which a device saves up characters, attempting to
transmit them only when the ENTER or RETURN key is pressed. The block mode of a
terminal supports page-mode applications. See page mode.
BPADPARMS. Block mode options, which can be set by the user, for configuring a
Packet Assembler/Disassembler (PAD).
buffer. Area of storage temporarily reserved for performing an input/output (I/O)
operation. It holds data to be transmitted and data received.
byte. String of eight bits.