The HP 3000 Series 900 computer supports a wide
range of useful peripheral devices. This manual describes how devices
which are connected to a DTC and communicate asynchronously (such
as terminals and serial printers) interact with the MPE/iX operating
system. It also describes how asynchronous devices can be controlled
programmatically through the use of system intrinsics. Only the
subset of intrinsics useful for control of asynchronous devices
is described here. For a complete listing of all the system intrinsics
available with MPE/iX see the MPE/iX Intrinsics Reference
Manual.
When you are programmatically controlling devices connected
to your system, it is vital that you have a basic understanding
of the way each specific device interacts with the computer. How
this interaction occurs depends on such diverse factors as baud
rate, transmission method and the purpose for which the device is
being used. In order for successful communications to take place,
the computer and the peripheral device must agree on the method
of communication being used and must know exactly what to expect
from each other.
This chapter provides an overview of how communications take
place between an MPE/iX system and the asynchronous serial devices
connected to it. The following topics are discussed:
The types of devices that communicate
in an asynchronous serial fashion.
The physical components of the Datacommunications
and Terminal Subsystem.
The software that governs Asynchronous Serial Communications.
The basic data communications concepts involved.
