SUBROUTINE CTERM

 CTERM is the central subroutine for controling the state of the graphics terminal. It is used to switch a graphics terminal in and out of the graphics and text modes. It is a dummy call when not in  terminal plotting mode. Note that not all options are available on all terminals. Results of operation of this routine is thus terminal dependent. In some cases the graphics and text modes are the same while in others, the mode is switched only at init/de-init. See the introduction to the documentation under terminal types. See also  .

  Note: for CTERM(2), the user will be prompted for a "clear screen". The reply may be "Y" for yes, "N" for no (the default), "Q" (quit), "S" (skip one), "P" (pass many), or "D" (dump). "Y" and "N" clear the screen as indicated and the program continues normally. A reply of "Q" permanently disables terminal screen plotting until the package is reinitialized by FRAME. A replot of "S" disables screen plotting until the next CTERM(2) call whereupon the "clear screen" prompt reappears as before. A reply of "P" is similar to "S", but the user will be prompted for the number of  CTERM(2) calls to pass before reissuing the prompt. In this manner multiple terminal screen "pages" can be skipped. A reply of "D" will enable a dump of the screen to the attached terminal printer (if supported on the particular terminal/printer). Note that during a skip that any changes of origin by PLOT, scale factors by  FACTOR or VFACTOR, or pen color or linetype will NOT take place.

CALL CTERM (iarg)

iarg (I): terminal operation code
          = 0 : initialize graphics mode on terminal
          = 1 : return terminal from graphics to text mode
          =-1 : return terminal text to graphics mode
          = 2 : return terminal to text mode, and prompt
                user for clear screen (see note above)
          =-2 : return terminal to text mode, clear graphics screen
          = 3 : clear text screen, leave in text mode
          =-3 : clear graphics screen, leave in terminal mode
          = 4 : dump graphics screen to printer
          =-4 : clear text, graphics, leave in graphics mode
          = 5 : turn off graphics screen, return to text mode
          =-5 : turn on graphics screen, return to graphics mode
          = 6 : toggle reverse video
          = 8 : de-initialize graphics terminal