PLOT(VI)                     3/10/75                     PLOT(VI)


     plot: tek, gsip, vt0 - graphics filters


     source | tek

     source | gsip

     source | vt0


     These commands produce graphical  output  on  the  Tektronix

     4014  terminal, the GSI or other Diablo-mechanism terminals,

     and the on-line storage scope respectively.  They  read  the

     standard  input  to  obtain plotting instructions, which are

     usually  generated  by  a  program  calling   the   graphics

     subroutines  described  in  plot  (VII).   Each  instruction

     consists of an  ASCII  letter  usually  followed  by  binary

     information.   A  plotting coordinate is transmitted as four

     bytes representing the x and  y  values;  each  value  is  a

     signed number transmitted low-order byte first.  The assumed

     plotting space is set  by  request.   The  instructions  are

     taken from

     m   move: the next four bytes specify the coordinates  of  a

        point to move to.  This is used before writing a label.

     p   point: the next four bytes specify  the  coordinates  at

        which a point is drawn.

     l   line: the next eight bytes are taken  as  two  pairs  of

        coordinates  specifying  the  endpoints  of  a line to be


     t   label: the bytes up to a new-line are written  as  ASCII

        starting at the last point drawn or moved to.

     a   arc: the first four bytes specify the center,  the  next

        four  specify  the  starting  point,  and  the  last four

        specify the end point  of  a  circular  arc.   The  least

        significant  coordinate  of the end point is used only to

        determine  the  quadrant.   The  arc  is  drawn  counter-

        clockwise.   This  command is not necessarily implemented

        on all (or even any) of the output devices.

     c   circle: The first four bytes specify the center  of  the

        circle, the next two the radius.

     e   erases the screen

     f   linemod: takes the following string as the type for  all

        future   lines.    The   types   are  `dotted,'  `solid,'

        `longdashed,'  `shortdashed,'  and   `dotdashed.'    This

        instruction   is   effective   only  with  the  Tektronix


     d   dotline: takes the first four bytes as  the  coordinates

        of  the  beginning  of a dotted line.  The next two are a

        signed x-increment, and the next two are  a  word  count.

        Following   are   the   indicated  number  of  byte-pairs

        representing words.  For each bit in this list of words a

        point  is  plotted  which  is  visible if the bit is `1,'

        invisible if not.  Each point is offset rightward by  the

        x-increment.   The  instruction  is effective only on the

        vt0 scope.


     plot (VII), graph (VI)