AM3270/TR3271 Reference Manual

Subdevices
A Closer Look at AM3270
3–2 086705 Tandem Computers Incorporated
The following figure shows how AM3270 might be used in a pass-through
configuration.
Figure 3-2. Example of AM3270 Pass-Through Configuration
AM3270
Comm Line
TR3271
x1
x2
(PTP)
(PTP)
Tandem NonStop System
Comm Line
IBM
Compatible
Host
007
3270 Devices and Controller
(CRT)
(PTP)
t3
t1
(PTP)
t2
3274/3274
t3
t1
t2
Subdevices This section discusses the ways in which AM3270 accesses subdevices. For a detailed
description of how to configure AM3270 subdevices, refer to the SCF Reference Manual
for AM3270 and TR3271.
Configuration and Control SCF is the only Tandem utility program that provides a conversational and
programmatic interface to AM3270 subdevices for both the C30.09 and D-series
3650/6100 CSS environments. For information about using SCF commands with
AM3270, refer to the SCF Reference Manual for AM3270 and TR3271.
Note The Communications Management Interface (CMI) can also be used for C-series 3650/6100 CSS
environments, but it has less functionality than SCF, and Tandem recommends that you use SCF.
Support for the CMI interface and 6202 controller are discontinued for AM3270 and TR3271 for D-series
releases.
Subdevice Access Individual subdevices may be accessed from an application process or from
subsystems supplied by Tandem, such as the command interpreter (TACL). Access of
an individual subdevice can occur even though the subdevice is merely one
component of a polled group of physical devices.
Application processes issue standard file-system requests (such as OPEN, READ, or
WRITE) to the subdevices. AM3270 processes these requests and performs the
required actions (the application uses the OPEN procedure to access the terminal; and
the application uses READ and WRITE requests to AM3270 to perform poll and select
operations on the line).