Configuring Systems for Terminals, Printers, and Other Serial Devices (32022-90051)

Chapter 9 177
Describing Asynchronous Devices
How Operation Modes Set Functionality
How Operation Modes Set Functionality
Six device operation modes can be used. Each has different capabilities
and is intended for a specific purpose. The six are as follows:
• System console
• Session-accepting devices
• Programmatic devices
• Spooled devices
• Slaved devices
• Uninterruptible Power Supply (UPS) devices on the DTC.
System Console
On CIO systems, the system console is the only device that is not
connected to the computer through a DTC. The computer is aware of its
existence from system initialization. It is connected to a special
interface card in the cabinet called the access port.
Although the system console is session-accepting, it has the following
added functionality:
• Receipt of console messages. The system console is the message
center for the computer. Messages can be informational, such as
notifying an operator when users log on or off the host. Messages can
also alert an operator to take an action, such as mounting a
magnetic tape on the tape drive so that its data can be accessed by a
user program.
• Execution of console commands requiring the console attention
character. These commands are called
[CTRL]-A commands. Using
[CTRL]-A, an operator can interrupt an action on the system console
to enter commands that will abort one or all users, answer console
requests, or shutdown the computer.
• Execution of other console commands. These commands are used for
system startup and shut down procedures.
Because the system console serves a specific purpose, the following
functionality is not provided:
• System console operation at 19200 bps. Supported speeds are 300,
1200, 2400, 4800, and 9600 bps.
• User block mode applications. Only block mode applications that use
VPLUS can run on the system console. NMMGR is supported on the
system console.