Using a separate terminal as graphics display

If necessary a second terminal can be used for the display of graphics. This may be useful if a dual-screen alpha/graphics terminal is not available for example, and you want to retain the display while continuing to issue SPECX commands.

This arrangement is set up using the SET-TERMINAL-DEVICE command, in which you nominate both the type of terminal and the VMS device name. For terminals connected directly to a VAX serial port this is quite straightforward. For terminals attached to DECSERVERs or similar devices the LAT services must be used to define a name for the particular port to which the terminal is connected. e.g., from the JCMT startup files...

   $!   Start LAT
   $    @SYS$MANAGER:LTLOAD
   $    LCP :== $SYS$SYSTEM:LATCP
   $!
   $!   Define LAT services
   $    LCP SET NODE/IDENT="JCMT MicroVax 3400"
   $    LCP SET SERVICE MWTVAX/IDENT='JCMT MicroVax 3400'
   $    LCP CREATE SERVICE JCMT/IDENT='JCMT Computing System"/STATIC_RATING=0
   $!
   $!   Define LAT ports
   :
   $    LCP CREATE PORT/APPLICATION LTA4:
   $    LCP SET PORT/APPLICATION/NODE=JCMT2/PORT=PORT_4 LTA4:
   :
   $    EXIT

Note that the graphics terminal cannot be accessed if it is already allocated to another process -- whether or not the process is owned by another user or by yourself.