Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

Chapter 1 33
Introduction
ASC Software Overview
ASC Software Overview
The Asynchronous Serial Communications software provides the
interface between the IEEE 802.3 LAN and the MPE/iX system.
Control
The software is included with the MPE/iX Fundamental Operating
System (FOS). MPE/iX system software mirrors its related hardware in
the sense that it is structured in modules, with each module handling
the control of a specific type of hardware device. These modules, or
managers, know which devices of their type are configured, or currently
connected through a DTC connection, and handle all functions related
to those devices. They manage terminal and printer I/O and are
responsible for detecting errors that take place during communications
and reporting them to the MPE/iX system. On LANs that do not include
an OpenView Workstation, the ASC managers also manage the
downloading and uploading of information for the DTCs configured on
the system.
The ASC managers define the characteristics of the devices they
control. They determine, among other things, the type of
communications protocol being used. The way in which the ASC
software expects devices to act is defined in part at configuration time,
but can be altered programmatically through use of the system
intrinsics described in this manual.
The ASC managers provide the interface between asynchronous devices
and the File System. The File System is the part of the MPE/iX
operating system that manages information being transferred or stored
with peripheral devices. More information on the File System and how
intrinsics are used to control devices can be found in Chapter 2,
“Controlling Asynchronous Devices Programmatically.”
Configuration
The MPE/iX system keeps track of all devices connected to it by means
of configuration files. The network configuration information
necessary to initialize and control the Datacommunications and
Terminal Subsystem (DTS) resides in the NMCONFIG.PUB.SYS
configuration file. This file is created through use of the Node
Management Configuration Manager (NMMGR) utility.
NMMGR is described in Using the Node Management Services (NMS)
Utilities, while Configuring Systems for Terminals, Printers, and Other
Serial Devices provides a detailed discussion of the configuration
process.