1 03/19/85  video_data_
 2 
 3 
 4 The video_data_ subroutine is a data segment containing information
 5 about the video system.
 6 
 7 
 8 Entry points in video_data_:
 9    (List is generated by the help command)
10 
11 
12 :Entry:  terminal_iocb:  03/19/85 video_data_$terminal_iocb
13 
14 
15 Function:  This is the terminal control switch IOCB pointer.  If the
16 video system is activated for the user's terminal, this pointer is
17 nonnull, and points to the IOCB for the switch user_terminal_.
18 
19 
20 declare video_data_$terminal_iocb pointer external static;
21 
22 
23 Notes:
24 User programs may use this pointer for two purposes:
25 
26 1. Inquiring as to whether the video system is activated, by checking
27    to see if the pointer is null.
28 
29 2. Determining the physical characteristics and capabilities of the
30    terminal.  This may be accomplished with the get_capabilities
31    control order, described under the window_io_ I/O module.  The
32    height and width returned will be that of the physical terminal
33    screen.
34 
35    No other manipulations of this switch are permitted.