User`s guide

2-27
Printers, Print Jobs, and Queues for Systems Administrators
Commands and Control Sequences
Terminfo Database
The terminfo database contains the capabilities and special features of a terminal device,
such as cursor positioning, initialization sequences, and key sequences that control specific
terminal operations. For supporte d terminals, the control sequence values are predefined in
the terminfo database. The control sequences that allow access to the AUX port are:
mc5=Value Instructs the terminal to send all data to the AUX port (Printer ON).
mc4=Value Restores output to the terminal (Printer OFF).
The control sequence values are terminal specific. For example, the printer command
sequences for an IBM 3151 terminal are:
mc5=^P^R
mc4=^P^T
In this example, ^P^R refers to the Ctrl–P Ctrl–R key sequence.
Adding Support for Nonsupported Terminals
The control sequences must be added to the terminfo database in the
/usr/share/lib/terminfo directory. To add the control sequence values for your terminal, edit
the appropriate *.ti file. Then compile th e file using the tic command. Refer to the
documentation supplied with your terminal for more information about control sequence
values.
The virtual printer database is a series of files that describe the way print requests should
be processed, such as the data stream to be delivered to the printer. User–configurable
attributes specific to terminal–at tached printers are defined in the virtual printer database
and are based upon the asynchronous communications adapter being used.
The virtual printer attributes are defined when the virtual printer is configured. The naming
convention for attributes unique to terminal–attached printers is yN, where N is an integer
greater than or equal t o 0. The value of y0 is reserved. It designates that the virtual printer
queue is configured for a terminal–attached printer and contains the hardware line discipline
for the terminal port. The sections that follow detail the adapter–specific virtu al printer
attributes for terminal–attached printers.
To change the attribute values on an existing virtual printer, use the Web-based System
Manager Devices fast path. You can also use the smit ps_lsvirprt fast path command.
Native, 8–Port, 16–Port, and Third–party Controllers
Native port (S1 or S2), 8–port and 16–port controllers do not provide hardware support for
terminal–attached printers and the hardware support for third–party controllers is unknown .
As a result, print files must be split into small data blocks. The mc5 control sequence
precedes each data block, which is in turn followed by the mc4 control sequence. When the
terminal receives the mc5 control sequence, all subseq uent data is routed to the AUX port
until an mc4 control sequence is received.
Data blocks sent to the terminal must be kept relatively small. Sending too many characters
to the tty at once may cause output to the printer to be mixed with the echo of what is typed
during the sending operation. A delay time between data block transmissions must also be
established to minimize data reception errors.
Native port, 8–port, 16–port, and third–party controllers have the following virtual printer
attributes for specifying block size and delay value: