dptg2(7) dptg2(7)
NAME
dptg2 - terminal multiplexer protocol
DESCRIPTION
The DPTG2 protocol is an SNI-specific terminal protocol for using BA47
and BA80 (9766) screens. Operation of PCs with DPTG2 protocol emula-
tion is also supported. Up to 16 virtual channels can be used on an
asynchronous V.24 line with this protocol.
Each of the virtual channels is available to the user as an indepen-
dent terminal in /dev/term. However, it is not possible to set the
physical line parameters with an ioctl system call. A flow control is
allowed for each channel, which prevents a buffer overflow in the
screen. Apart from the restriction regarding the physical parameters
of the line, a complete functionality of UNIX system V Release 4 is
offered.
The components of DPTG2 are contained in the Reliant UNIX package
SIdptg2. This package is mounted in the directory /opt/dptg2.
The DPTG2 protocol offers the following features:
- The DPTG2 protocol allows the connection and startup of DPTG2 ter-
minals. Operation of the PROM software for command entry (ASCII
characters > 0x20 and control characters CR, LF) is supported.
Operation of VT terminals with the DPTG2 protocol is not supported.
If these terminals are used on lines configured for DPTG2 termi-
nals, it may be necessary to generate a new operating system.
- The control characters XON and XOFF are used only for the flow con-
trol of the physical line.
- If the terminal does not support the DPTG2 protocol (e.g. because a
workstation program has not yet been loaded), the channels respond
to the system calls in the same way that they would if the terminal
was switched off.
- The setup procedure for the terminals is transparent to the user.
The channels are only cleared when the terminal has been success-
fully set up and when it is ready for the DPTG2 protocol, thus as
if the terminal was already switched on. None of the channels is
used for the setup (as was the case with the previous protocol ver-
sion, DPTG1).
- The DPTG2 protocol can be used for asynchronous V.24 lines as well
as for TCP/IP network connections. This means that the screens can
be connected either directly to the Reliant UNIX system, or
remotely to a terminal server or DOS-PC with DPTG2 emulation.
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The DPTG2 protocol is defined for an asynchronous connection between
the workstation program in the terminal and a STREAMS multiplexer in
the Reliant UNIX host. On the host side, the DPTG2 multiplexer is con-
nected with a TTY driver or a TCP/IP socket (using the system call
ioctl(ILINK)) after the terminal has been recognized as being avail-
able. The DPTG2 connection between host and screen is set up by a mon-
itor as part of the SAF (Service Access Facility). This monitor is
called muxmon and is part of the DPTG2 package.
The DPTG2 monitor muxmon can be managed with the muxadm(1M) command,
which is included in the DPTG2 package. It supports the special
features of the DPTG2 monitor. muxadm is used by the termadd(1M) com-
mand for the configuration of a DPTG2 channel. Commands are forwarded
to sac(1M) during configuration, whereby the channel is incorporated
in the DPTG2-specific administration. A monitor incarnation can be
created and started by termadd(1M) if necessary.
The termadd(1M) command is not included in the DPTG2 package, as it
can also be used to configure other types of screen.
The muxmon(1M) monitor not only sets up a DPTG2 connection to the
screen, but also loads the screen if necessary. It also monitors the
status of the screen. If the monitor is switched off (or the network
connection crashes), the ILINK link between the multiplexer and
driver (or socket in the case of remote connections) is removed. The
DPTG2 channel responds to system calls in the same way that it would
if the terminal were switched off.
A new feature of DPTG2 is that, unlike DPTG1, the terminal setup for
an application is transparent, and the CLOCAL functionality is avail-
able on a channel-specific basis.
DIAGNOSTICS
The DPTG2 components generate status and error messages for Logging
V3.0 for diagnostic purposes. The component number for messages in the
area of DPTG2 is 36 (SIdptg2).
The error numbers for the individual components of the DPTG2 system
are:
____________________________________________
| Label | Name | Error number |
|_______________|___________|_______________|
| Multiplexer | dptg2mux | 1 |
| Link monitor | muxmon | 6 |
| Admin command | muxadm | 7 |
|_______________|___________|_______________|
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NOTES
The workstation programs, which can be loaded onto the BA80, are not
included in the SIdptg2 package. By default, they are under /opt/xb.
If they are not available, the SIxb package must be installed.
The SIdptg2 package dos not have any commands for the configuration of
DPTG channels. These commands can be found in the SIterms package.
FILES
/opt/dptg2
/opt/xb
SEE ALSO
muxadm(1M), muxmon(1M), sac(1M), termadd(1M), ioctl(2).
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