C
C===========================================================================
C
C	MATROX TEK 4010 graphics emulator (not using internal scaling)
C
C	8.0" x 6.0"   (1235 x 240) via small TEK (975 x 739)
C
C===========================================================================
C
	JDEV = JDEV - 1
	IF (JDEV .NE. 0) GOTO 6999
C
	IF ((IMODE .LT. -5) .OR. (IMODE .GT. 6)) RETURN
	GOTO (6000,6005,6010,6020,6030,6040,6050,6060,6070,6090,
	1				6100,6200),IMODE+6
C
C	mode -5: we exist
C
6000	X = 1.0
	GOTO 90
C
C	mode -4: initialize
C
6005	CALL GTATT(LUNGRP)		! and attach the terminal, set up loon
	GOTO 90
C
C	mode -3: return screen size
C
6010	X = 8.0
	Y = 6.0
	GOTO 90
C
C	mode -2: alpha cursor position
C
6020	CALL GTTEKI(IX,IY,I,2)		! request alpha cursor
	X = IX     / 121.875
	Y = IY-16 /  115.333		! this thing displays 16-255 (?)
	GOTO 90
C
C	mode -1: graphics cursor position
C
6030	CALL GTTEKI(IX,IY,I,1)		! request graphics cursor
	X = IX     / 121.875
	Y = IY-16 /  115.333
	XT = XTLAST
	YT = YTLAST
	GOTO 6050			! reposition cursor with a dark vector
C
C	mode 0: clear screen
C
6040	CALL GT(ESCAPE)			! make sure we're in transparent mode
	CALL GT('2')
	CALL GT(ESCAPE)			! make sure we're in ANSI mode
	CALL GT('<')
	CALL GT(ESCAPE)			! erase all
	CALL GT('[2J')
	CALL GT("35)			! now to 4010 mode
	CALL GT(ESCAPE)			! tell it we're going to configure it
	CALL GT('TA')
	CALL GT(ESCAPE)			! nibs = 1
	CALL GT('TB')
	CALL GT(ESCAPE)			! solid line
	CALL GT('`')
	CALL GT(ESCAPE)			! exit configure mode
	CALL GT('T@')
	CALL GT(ESCAPE)			! erase graphics memory
	CALL GT("14)
	CALL GT(ESCAPE)			! and back to transparent mode
	CALL GT('2')
	CALL GTF			! flush the buffer (do it)
	LINPAT = -1			! initialization does this ...
	NIBS = 1
	GOTO 90
C
C	mode 1: unwritten vector
C
6050	CALL GT("35)			! <GS> invokes graphics; dark vect 1st
	GOTO 6080
C
C	mode 2: written vector
C
6060	GOTO 6080			! must assume in graf mode.  do it.
C
C	mode 3: point plot
C
6070	CALL GT("34)			! <FS> invokes point plot mode
C
C	modes 1,2,3: send out the X,Y coordinates
C
6080	IX = MIN1(975.,AMAX1(0.,121.875*XT+0.5))
	IY = MIN1(692.,AMAX1(0.,115.333*YT+0.5)) + 16
	CALL GTTEK(IX,IY)
	GOTO 90
C
C	mode 4: finish the plot
C
6090	CALL GT("35)			! dark vector
	CALL GTTEK(0,692)		!  to the top left corner
	CALL GT("15)			! enter alpha mode
	CALL GT(ESCAPE)			! enter transparent mode
	CALL GT('2')
	CALL GTF			! flush the buffer
	CALL GTATT(-LUNGRP)		! deattach the terminal
	CALL CLOSE(LUNGRP)
	GOTO 90
C
C	mode 5: set nibs (X;pen width) and line pattern (Y)
C
6100	IX = X
	IF (IX .EQ. NIBS) GOTO 6102
	NIBS = IX
	IF (NIBS .LT. 1) NIBS = 1
	IF (NIBS .GT. "37) NIBS = "37
	CALL GT(ESCAPE)			! set configure mode
	CALL GT('TA')
	CALL GT(ESCAPE)			! set the pen width
	CALL GT('Sa ')
	CALL GT("100+NIBS)		! This is the actual width
	CALL GT(ESCAPE)			! get out of configure mode
	CALL GT('T@')
C
C	line pattern generation (only one set of on/off distances allowed)
C
6102	IY = Y					! get line pattern
	IF (IY .EQ. LINPAT) GOTO 90		! if set, don't change
	LINPAT = IY				! set for later
	CALL GT(ESCAPE)				! set up configure mode
	CALL GT('TA')
	CALL GT(ESCAPE)				! init. for new pattrn
	IF (LINPAT .NE. -1) GOTO 6105
	CALL GT('`')				! use solid line
	GOTO 90
C
C	non-solid line - figure it out
C
6105	CALL GT('D ')
	YT = Y
	IF (YT .LT. 0) YT = YT + 65536.0	! YT = real 0-65k
	IY = 1
	IX = 1					! counts # bits on/off
C	main loop - count down from the top
	DO 6140 I=15,0,-1
	XT = 2.0**FLOAT(I)			! XY = value of a bit
	N = 0					! N will be the bit
	IF ((XT - 0.1) .GT. YT) GOTO 6110	! account of roundoff
	N = 1					! this bit was set
	YT = YT - XT				! reduce our counter
C	now, N is the value of the next bit, YT reduced if needed
6110	IF (N .NE. IY) GOTO 6120
C	we're counting this type (IY=0 ==> off ==> N=0, etc)
	IX = IX + 1
	GOTO 6140
C	bits changed from on to off, or vise versa.  ship out bits, set up new
6120	IF (IY .EQ. 0) GOTO 6150
	CALL GT("140+IX)
	CALL GT(' ')
	IY = 0					! set up to count the bits off
	IX = 1
6140	CONTINUE
C
	IF (IY .EQ. 0) GOTO 6150		! go send out the off count
	CALL GT("140+IX)			! ship out last of the ons
	CALL GT(' ')
	IX = 1					! set up at least on off bit
6150	CALL GT("100+IX)			! send out the off count
	CALL GT(ESCAPE)				! get out of configure mode
	CALL GT('T@')
	GOTO 90
C
C	mode 6: identify ourself
C
6200	WRITE (LUN,6210)
6210	FORMAT('+	VT100 with MATROX adapter')
	GOTO 90
C
C	all done - get ready for the next
C
6999	CONTINUE