SUBROUTINE PLTX(N)
C     SUBROUTINE PLTX(N) transmits relative mode primitive commands
C     to the Houston Instruments HIPLOT DMP-4, etc. DMPL plotters.
C
C     ORIGINAL PROGRAM BY C. E. COHN FOR THE DDP-24, MODIFIED
C     FOR THE PDP-11/34 BY J. MORMAN, AUG., 1979
C     PLOTTER X AND Y MOTIONS ARE IN STEPS OF 0.005 INCH,
C     WITH DIAGONAL MOTIONS OF SQRT(2)*0.005 INCH.
C  
C     MODIFIED BY PAUL MURPHY, FEB., 1981 FOR INCLUSION
C     IN THE FOURIER DATA ANALYSIS PROGRAM
C
C 4-Nov-82 DVJensen - Converted to call PLTOUT and overall output
C     string sizes reduced.  
C 9-Nov-82 DVJensen - Converted to call PENUP and PENDWN.
C
C     THE INTEGER N SPECIFIES THE OPERATION AS FOLLOWS:
C     N =  0, INITIALIZE, NO PLOTTER MOTION
C       =  1, STEP IN -Y DIRECTION 
C       =  2, STEP IN +Y DIRECTION 
C       =  4, STEP IN -X DIRECTION 
C       =  5, DIAGONAL STEP IN -X,-Y DIRECTION 
C       =  6, DIAGONAL STEP IN -X,+Y DIRECTION 
C	=  8, STEP IN +X DIRECTION 
C	=  9, DIAGONAL STEP IN +X,-Y DIRECTION 
C	= 10, DIAGONAL STEP IN +X,+Y DIRECTION 
C	= 16, LOWER PEN 
C	= 32, RAISE PEN 
      IMPLICIT INTEGER*2 (I-N)
C
      INTEGER*2 ISUB(9),LENGTH(9)
      LOGICAL*1 LWORD(8),SP(2),LDUMU
      REAL*8 DCHAR(9),DWORD
      EQUIVALENCE (DWORD,LWORD(1))
      DATA ISUB/0,1,2,4,5,6,8,9,10/
      DATA DCHAR/' ;:R    ','0,-1    ','0,1     ','-1,0    ',
     $'-1,-1   ','-1,1    ','1,0     ','1,-1    ','1,1     '/
      DATA LENGTH/4,5,4,5,6,5,4,5,4/
C LENGTH defines the number of characters in each DCHAR element to output.
      DATA SP/' ',','/
C
      IDIFF=N-16
      IF(IDIFF) 5,6,7
6     CALL PENDWN
      RETURN
C
7     CALL PENUP
      RETURN
C
5     NSEL=0
      DO 2 I=1,11
      NSEL=NSEL+1
      IDIFF=ISUB(I)-N
      IF(IDIFF) 2,3,2
2     CONTINUE
3     DWORD=DCHAR(NSEL)
      CALL PLTOUT( LWORD,LENGTH(NSEL) )
71    RETURN
      END