.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     CRT DRIVER USER'S MANUAL                                  *
.COMMENT                                                               *
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     TITLE AND REVISION PAGES                                  *
.COMMENT                                                               *
.COMMENT****************************************************************
.NO NUMBER
.CENTER ;MOSTEK CRT DRIVER USER'S GUIDE
.PAGE
.CENTER ;MOSTEK CRT DRIVER USER'S GUIDE
.PAGE
.LITERAL





















.END LITERAL
.CENTER ;MOSTEK CRT DRIVER USER'S GUIDE
.SKIP 3
.CENTER ;FOR
.SKIP 3
.CENTER ;SOFTWARE RELEASE 2.1
.SKIP 3
.CENTER ;BY
.SKIP 3
.CENTER ;KEVIN KLUGHART
.PAGE
.CENTER 70;CONTENTS
.SKIP 2
.REQUIRE "CRT.RNT"
.AUTOPARAGRAPH
.AUTOSUBTITLE
.FLAGS CAPITALIZE
.LEFT MARGIN 0
.NUMBER PAGE 1
.PAGE SIZE 58,60
.PAGE
.NUMBER PAGE 1
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     GENERAL INFORMATION                                       *
.COMMENT                                                               *
.COMMENT****************************************************************
.SUBTITLE MOSTEK VAX/RJE USER'S MANUAL
.CHAPTER GENERAL INFORMATION
.DISPLAY CHAPTER
.DATE
.PAGE
.HEADER LEVEL 1 SUMMARY
.SKIP 5

     This manual describes the operation of the VAX/VMS
universal CRT terminal driver interface
currently implemented on the
VAX-11/780 computer system at MOSTEK.  This document
supersedes all previous documentation concerning
the CRT (VT100) driver, whether written or oral.

     This is release 2.1 of the terminal driver package.
Release 1.0 (08-03-79) supported only VT100 video terminals
and was very narrow in its scope of operation and 
available functions.  This release has been renamed CRT
driver to emphasize the new transparency which comes with
the inclusion of other video as well as hardcopy terminals
in the range of supported interface devices.  This release
is designed to support the following terminals:
.SKIP
.LEFT MARGIN +10
.NOFILL
DEC VT100 with advanced video option (AVO)
DEC VT52
DEC LA36 DECWRITER II
DEC LA120 DECWRITER III
Datamedia DT80/1
Intelligent Systems Corp. 8001 color graphics
Hewlett-Packard HP264X series
PRINTRONIX Model 300/600 Printers
QUME Corp. SPRINT 5 series
.SKIP
.FILL
.LEFT MARGIN -10
In addition, for those terminals which support auxiliary I/O ports,
the new release of the CRT driver fully supports BOTH terminals
in such a configuration.  This capability is designed to be
upward compatible with future support of several on-line color
graphics terminals tied to the auxiliary I/O ports of the existing
video terminals at Mostek.

     Users of this software package are urged to read fully the 
following documentation, as there have been many changes in this
software with release 2.1.  The major changes involve the following:
.SKIP
.LEFT MARGIN +10
.NOFILL
1.  Support of more terminals
2.  Support of auxiliary I/O interface
3.  Dynamic determination of terminal type
4.  Increased driver speed (2X to 5X)
5.  Reduction of unnecessary I/O
6.  Cursor position report
7.  Elimination of terminal width limits
8.  Addition of SENSE MODE and SET MODE
9.  Elimination of auxiliary I/O bugs
.FILL
.LEFT MARGIN -10
.PAGE
.HEADER LEVEL 1 DESCRIPTION
.SKIP 5

     The CRT driver was designed in the summer of 1979 as a unified
and consistent method of accessing the graphics and control functions
of the VT100 terminal from high level languages such as FORTRAN, COBOL,
BASIC and PASCAL.
To this end a software package consisting of approximately 40
entrypoints was developed to interface the general FORTRAN or COBOL
user with the advanced screen control and graphics functions of the VT100 
and DT80/1 terminals.
In this fashion, the burdon of issuing control and graphics
commands could be carried by a set of utility subroutines, thus freeing
the applications programmer to concentrate on the task of the 
applications program.  In addition, this method of unifying the control
functions within one single piece of software serves to reduce the
amount of software that has to be written and in addition tends to make
the software which is written easier to read, as the control
function entrypoints have standardized naming conventions.
     
     This method of CRT control is fast, efficient, and will reduce the
software development time of most graphics applications by 100_% or more.
In addition, a great deal of hardware compatibility can be maintained
with respect to future display terminals.  This hardware compatibility
is the result of a sharp division between interfacial and algorithmic
code segments.  As stated by Harvy A. Cohen and Rhys S. Francis:
.SKIP
.LEFT MARGIN +5
.RIGHT MARGIN -5
To make any headway on the problem of code production and update it
is necessary to examine the nature of the software changes induced
by hardware configuration changes.  Major portions of any well-structured
code are unaltered by such changes.  To eliminate once and for all the
sheer messiness of having to make innumerable tiny alterations in what
had been functional code, we need to erect a barrier within the software.
Outside the barrier lies software not affected by hardware configuration
changes.  This software is essentially configuration-free; we call it
algorithmic software.  Within the barrier lies the intefacial software,
including such items as input, output, and timing routines, special
execution mode routines, and interrupt handlers.  Our development
strategy requires that properly constructed programs should never
directly penetrate the barrier between algorithmic and interfacial
code.  Instead, all communication between the two must be via 
specially provided bridges or links.
.SKIP
COMPUTER, February, 1979
.LEFT MARGIN -5
.RIGHT MARGIN +5
.SKIP

     It is the function of the CRT driver to provide such bridges or
links for terminal graphics and control functions.  Although the
software is relatively young, it has proven worthy of CAD
standardization as the unified method of providing terminal
control functions in FORTRAN and COBOL programs.

     Due to the unique structure of the CRT driver, the addition
of additional terminal types in the knowledge base of the driver
is extremely simple.  Requests for such inclusions should be made
to the author.
.PAGE
.HEADER LEVEL 1 STRUCTURE
.SKIP 5

     The CRT driver is structured as a set of several VAX/VMS
FORTRAN V2.0 programs which contain a single entrypoint for
each function required by the terminal hardware to be
controlled.  This software is located in SYS$SYSDISK:[SYSLIB.MOSTEK]
in a source file named CRT.FOR.  This module is compiled and then
inserted in the SYS$SYSDISK:[SYSLIB]STARLET.OLB system object code
library.  At this point the entrypoints become globally defined, and
are automatically included in a user's program at LINK time if they
are referenced.  This allows the general user population the benefits
of driver package with none of the overhead associated with its
initial generation and debugging.  Users are encouraged to examine
and study the [SYSLIB.MOSTEK] subdirectory and the CRT driver
module CRT.FOR.  This source module conforms to strict Mostek coding
practices and should serve as a guide to writing effective and well
documented user application programs.
.PAGE
.CHAPTER USING THE CRT DRIVER
.DISPLAY CHAPTER
.PAGE
.HEADER LEVEL 1 Initialization and Exit
.SKIP 5

     The initialization and exit routines of the CRT driver have
changed with release 2.0.  The philosophy of release 1.0 was to
initialize the terminal parameters for a specific configuration
.INDEX <CRT__INITIALIZE
when the CRT__INITIALIZE routine was called.  This strategy has been
changed to the following:
.LEFT MARGIN +5
.RIGHT MARGIN -5
.SKIP
"The user is responsible for setting the
required terminal parameters for his particular application program.
No assumptions should be made as to the current terminal configuration
except those stated in the MOSTEK TERMINAL CONFIGURATION FIRMWARE 
STANDARD.  Prior to exit, the user should under software control restore
the desired terminal configuration to the user's terminal.  The
CRT driver will make no attempt to perform such a restoration.
.SKIP
With respect to the software status of the user terminal, upon
initialization the CRT driver will save the current terminal mode
settings, and upon exit these mode settings will be restored to their
original values.  The user is free  to modify these mode settings
at will in the interval between initilization and exit."
.SKIP
.LEFT MARGIN -5
.RIGHT MARGIN +5
.PAGE
     In addition to the above initialization procedures
the user is responsible for the initialization of a local process
symbol SYS$TERMINAL which defines the logical terminal type and any
auxiliary I/O port which may be attached to the main terminal.
This symbol should be defined before any program using the CRT
driver is executed, and may be defined in the user's LOGIN.COM
procedure file.
This symbol is decoded at run-time to determine the specific terminal
type.  The format for definition of the process terminal type is as 
follows:
.SKIP
.INDENT +10
$ TERMINAL term__type[.aux__io__port]
.SKIP
Where term__type and aux__io__port are one of the following:
.SKIP
.LEFT MARGIN +10
.NOFILL
1.  VT100
2.  VT52
3.  LA36
4.  LA120
5.  DT80
6.  ISC_8001
7.  HP264X
8.  PRINTRONIX
9.  QUME
.FILL
.LEFT MARGIN -10
.PAGE
.HEADER LEVEL 2 CRT__INITIALIZE
.SKIP 5

     This routine initializes the CRT driver interface to the
user terminal.  Two I/O channels are associated with the user
terminal, SYS$COMMAND for all terminal input and SYS$OUTPUT
for all output.  Once these channels are successfully assigned,
the CRT driver obtains the current VAX/VMS process terminal modes
.INDEX <CRT__EXIT
which are then saved for later restoration in the CRT__EXIT
entrypoint.
.PAGE
.HEADER LEVEL 2 CRT__EXIT
.SKIP 5

     This routine terminates CRT driver processing and MUST be the
last CRT driver routine called before the process utilizing the
driver terminates processing.  This entrypoint restores VAX/VMS
terminal mode characteristics to their state at initialization,
deassigns all I/O channels, and reset internal terminal configuration
parameters.
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     CHARACTER I/O FUNCTION COMMANDS                           *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER CHARACTER I/O FUNCTION COMMANDS
.DISPLAY CHAPTER
.PAGE

     This chapter describes the various character I/O functions
which are available through the CRT driver.  These character I/O
functions enable the user to READ, POLL, or WRITE to the current
terminal using various forms of carriage control.  These I/O functions
are much more versatile than their FORTRAN counterparts, and enable
the user to perform realtime character processing on a byte-by-byte
basis in addition to the conventional FORTRAN record oriented method
of processing terminal character I/O.

     Please note that as of release 2.0, the character input/output
commands do not function exactly as those of release 1.0.  The
changes in functionality reflect the revised philosophy of the 
CRT driver as of release 2.0.  This philosophy is one of supporting
both character I/O as well as record I/O, but with different
entrypoints which emulate the FORTRAN equivalents.
.PAGE
.HEADER LEVEL 1 CHARACTER INPUT COMMANDS
.SKIP 5

     This section describes the various character input commands
which are included within the CRT driver.  It should be noted that
these commands are divided into two catagories.  The first category
emulates the FORTRAN READ statement but is faster.  The second category
is byte-oriented and allows the user to read not only the character
string input by the user, but also the terminating character which
terminated the command line.  Please note that all user character
strings are blank filled prior to actual character input from the
user terminal.
.PAGE
.INDEX <CRT__READ
.HEADER LEVEL 2 CRT__READ(STRING)

     This entrypoint enables the user to emulate the FORTRAN READ
statement by reading a character string from SYS$COMMAND and returning
this string minus any terminating characters to the STRING argument
specified by the user.
.INDEX <CRT__INPUT
.HEADER LEVEL 2 CRT__INPUT(STRING)

     This entrypoint enables the user to read a character string from
SYS$COMMAND and return it intact with all entered data including the
termination sequence.  To determine the actual number of characters
entered, interrogate the quadword I/O status block with a call to
.INDEX <CRT__IO__STATUS
CRT__IO__STATUS.
.INDEX <CRT__POLL
.HEADER LEVEL 2 CRT__POLL(STRING,TIME__PERIOD)

     This entrypoint enables the user to read a character string from 
SYS$COMMAND with a specified timeout period after which the read
operation aborts and control is returned to the user program.  
.INDEX <CRT__INPUT
Functionally equivalent to the CRT__INPUT entrypoint except that
this entrypoint includes the INTEGER*4 TIME__PERIOD argument which specifies
the read timeout period in seconds. Note that if the TIME__PERIOD
argument has a value of zero, the VMS system QIO read will assume
.INDEX <CRT__TYPEAHEAD
a time period of one (1) second.  See the CRT__TYPEAHEAD entrypoint
for related information concerning polling of the user typeahead buffer.
.PAGE
.HEADER LEVEL 1 CHARACTER OUTPUT COMMANDS
.SKIP 5

     This section describes the various character input commands
which are included within the CRT driver.  It should be noted
that these commands are divided into two categories.  The first
category involves multiple byte output transfers.  
This category includes both a FORTRAN emulated WRITE command
which includes pre-output carriage control
as well as a byte oriented PRINT command which suppresses
all carriage control. The second
category includes all single byte transfers.  
This category includes commonly used single byte commands such
as the BELL character and horizontal TAB character.
.PAGE
.HEADER LEVEL 2 MULTIPLE BYTE OUTPUT COMMANDS
.INDEX <CRT__WRITE
.HEADER LEVEL 3 CRT__WRITE(STRING)

     This entrypoint enables the user to transfer the character
argument STRING to the display surface.  This entrypoint emulates
the FORTRAN WRITE statement in that prior to the output of the 
argument STRING, the cursor is advanced to the next row (line)
and placed at column 1.  This is accomplished by transferring a carriage
return/linefeed (CRLF) sequence prior to the output of the STRING argument.
.INDEX <CRT__PRINT
.HEADER LEVEL 3 CRT__PRINT(STRING)

     This entrypoint enables the user to transfer the character
argument STRING to the display surface at the current cursor row and
column position. This enables character data data to be placed anywhere
on the display surface with no carriage control preceeding or
following the data transfer.
.INDEX <CRT__LARGE
.HEADER LEVEL 3 CRT__LARGE(STRING)

     This entrypoint enables the user to transfer the character 
argument STRING to the display surface at the current line in
double-height double-width format.  This entrypoint is only valid for
VT100 and DT80/1 terminals.
.PAGE
.HEADER LEVEL 2 SINGLE BYTE OUTPUT COMMANDS
.INDEX <CRT__ASCII
.HEADER LEVEL 3 CRT__ASCII(ASCII__CODE)

     This entrypoint enables the user to transfer the ASCII byte
specified by the INTEGER*4 argument ASCII__CODE to the user terminal
at the current row and column position. No carriage control is
performed either prior to or after the single byte transfer.
.INDEX <CRT__BELL
.HEADER LEVEL 3 CRT__BELL

     This entrypoint transfers the ASCII BELL character ('07'X) to
the user terminal at the current row and column position.
.INDEX <CRT__TAB
.HEADER LEVEL 3 CRT__TAB

     This entrypoint transfers the ASCII horizontal TAB character
('09'X) to the user terminal at the current row and column position.
This forces the terminal to advance to the next horizontal
physical tab stop.
.INDEX <CRT__LINEFEED
.HEADER LEVEL 3 CRT__LINEFEED

     This entrypoint transfers the ASCII LINEFEED character ('0A'X)
to the user terminal at the current row and column position.
.INDEX <CRT__VFU
.HEADER LEVEL 3 CRT__VFU

     This entrypoint transfers the ASCII vertical tab (VT) character
('0B'X)
to the user terminal at the current row and column position.  This
forces the terminal to advance to the next vertical physical tab stop.
.INDEX <CRT__FORMFEED
.HEADER LEVEL 3 CRT__FORMFEED

     This entrypoint transfers the ASCII FORMFEED character
('0C'X) to the user terminal at the current row and column position.
This forces the terminal to advance to the next physical page
defined by the top-of-form indicator.
.INDEX <CRT__RETURN
.HEADER LEVEL 3 CRT__RETURN

     This entrypoint transfers the ASCII carriage return (CR) character
('0D'X) to the user terminal at the current row and column position.
This forces the terminal to move the cursor to column 1 of the current
line.
.INDEX <CRT__NEXT__LINE
.HEADER LEVEL 3 CRT__NEXT__LINE

     This entrypoint transfers the ASCII characters carriage return/linefeed
to the user terminal at the current row and column position.  This
advances the current row (line) position and sets the current column 
position to 1, effectively starting a new display line.
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     SCREEN CONTROL FUNCTIONS                                  *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER SCREEN CONTROL FUNCTIONS
.DISPLAY CHAPTER
.PAGE
.SKIP 5

     This chapter describes the various screen control functions performed
by the CRT driver.  These screen control functions are logically
divided into cursor movement, line size, character attribute, erasing,
and special display commands.
.PAGE
.HEADER LEVEL 1 HORIZONTAL AND VERTICAL MARGIN COMMANDS
.SKIP 5

     This section describes the various horizontal and vertical margin
commands which are included within the CRT driver.  It should be noted
that the row and column counts referenced within this and following
chapters are defined such that row 1 column 1 is the top left-hand
corner of the display surface and is defined as the origin for
absolute cursor movement commands. This is consistent with the ANSI
standards X3.64 1977 and X3.41 1974.
.PAGE
.INDEX <CRT__MARGIN
.HEADER LEVEL 2 CRT__MARGIN(LEFT,RIGHT)

     This entrypoint sets the logical horizozntal 
left margin to LEFT and the logical horizontal right margin to RIGHT.
This determines the physical size in columns of the display surface.
.INDEX <CRT__REGION
.HEADER LEVEL 2 CRT__REGION(TOP,BOTTOM)

     This entrypoint sets the logical vertical top margin to TOP
and the logical vertical bottom margin to BOTTOM.  This determines
the physical size in rows (lines) of the display surface or 
scrolling region.
.INDEX <CRT__FORM__LENGTH
.HEADER LEVEL 2 CRT__FORM__LENGTH(LENGTH)

     This entrypoint sets the logical form length in lines to LENGTH
and in addition resets the top-of-form flag on the associated terminal.
This functionally determines the physical size in rows (lines) of
the display surface or scrolling region and in addition defines 
the physical line to be associated with top-of-form.
.PAGE
.HEADER LEVEL 1 CURSOR MOVEMENT COMMANDS
.SKIP 5

     This section describes the various cursor movement commands which
are included within the CRT driver.  It should be noted that the 
row and column counts referenced within this and following chapters
are defined such that row 1 column 1 is the top left-hand corner of
the display surface and is defined as the origin for 
absolute cursor movement commands.  This is consistent with the ANSI
standards X3.64 1977 and X3.41 1974.
.PAGE
.INDEX <CRT__HOME
.INDEX <CRT__HOME__UP
.HEADER LEVEL 2 CRT__HOME, CRT__HOME__UP

     This entrypoint positions the cursor at row 1, column 1. This 
position is defined as the top left-hand corner of the display surface.
.INDEX <CRT__HOME__RIGHT
.HEADER LEVEL 2 CRT__HOME__RIGHT

     This entrypoint positions the cursor at row 1, column COLMAX,
where COLMAX is defined as the maximum column number.  This position is
defined as the upper right-hand corner of the display surface.
.INDEX <CRT__HOME__DOWN
.HEADER LEVEL 2 CRT__HOME__DOWN

     This entrypoint positions the cursor at row ROWMAX, column 1,
where ROWMAX is defined as the maximum row number.  This position 
is defined as the lower left-hand corner of the display surface.
.INDEX <CRT__HOME__BOTTOM
.HEADER LEVEL 2 CRT__HOME__BOTTOM

     This entrypoint positions the cursor at row ROWMAX, column COLMAX,
where ROWMAX is defined as the maximum row number and COLMAX is
defined as the maximum column number.  This position is defined as
the lower right-hand corner of the display surface.
.PAGE
.INDEX <CRT__MOVE__UP
.HEADER LEVEL 2 CRT__MOVE__UP(COUNT)

     This entrypoint moves the cursor up 'COUNT' lines. No screen
wraparound is performed.  No screen scrolling is performed.
.INDEX <CRT__MOVE__DOWN
.HEADER LEVEL 2 CRT__MOVE__DOWN(COUNT)

     This entrypoint moves the cursor down 'COUNT' lines.  No screen
wraparound is performed.  No screen scrolling is performed.
.INDEX <CRT__MOVE__RIGHT
.HEADER LEVEL 2 CRT__MOVE__RIGHT(COUNT)

     This entrypoint moves the cursor right 'COUNT' columns.  No screen
wraparound is performed.  No character erasing is performed.
.INDEX <CRT__MOVE__LEFT
.HEADER LEVEL 2 CRT__MOVE__LEFT(COUNT)

     This entrypoint moves the cursor left 'COUNT' columns.  No screen
wraparound is performed.  No character erasing is performed.  
.INDEX <CRT__MOVE
.HEADER LEVEL 2 CRT__MOVE(ROW,COLUMN)

     This entrypoint moves the cursor to a specified row and column.
No argument bounds checking is performed. (1,1) is defined as the top
left-hand corner of the display surface. (ROWMAX,COLMAX) is the 
maximum effective display surface area.
.INDEX <CRT__POSITION
.HEADER LEVEL 2 CRT__POSITION(ROW,COLUMN)

     This entrypoint enables the user to inquire as to the current
position of the cursor on the screen.  The same restrictions in
ranging for ROW and COLUMN apply here as were stated in the CRT__MOVE
entrypoint.  If the current terminal does not support cursor position
report, arguments ROW and COLUMN will both return 0 on exit.
Please note that escape sequence recognition and validation must be
enabled for this entrypoint to function properly.  See entrypoints
.INDEX <CRT__ESCAPE__ON
.INDEX <CRT__ESCAPE__OFF
CRT__ESCAPE__ON and CRT__ESCAPE__OFF.
.PAGE
.INDEX <CRT__INDEX
.INDEX <CRT__INDEX__DOWN
.HEADER LEVEL 2 CRT__INDEX, CRT__INDEX__DOWN

     This entrypoint moves the cursor down one line and scrolls the
display area one line up if the cursor is located on the last logical
line of the display area.
.INDEX <CRT__INDEX__NEXT
.HEADER LEVEL 2 CRT__INDEX__NEXT

     This entrypoint moves the cursor to the first column of the next
line on the display surface, scrolling the display area one line up if
the cursor is located on the last logical line of the display area.
.INDEX <CRT__INDEX__UP
.HEADER LEVEL 2 CRT__INDEX__UP

     This entrypoint moves the cursor up one line and scrolls the 
display area one line down if the cursor is located on the first logical
line of the display area.
.INDEX <CRT__STORE
.HEADER LEVEL 2 CRT__STORE

     This entrypoint saves the current cursor position and attributes
for a later restoration by CRT__RESTORE.
.INDEX <CRT__RESTORE
.HEADER LEVEL 2 CRT__RESTORE

     This entrypoint restores the cursor positon and attributes saved
by a previous call the CRT__STORE.
.COMMENT****************************************************************
.COMMENT     TAB STOP COMMANDS                                         *
.COMMENT****************************************************************
.PAGE
.HEADER LEVEL 1 TAB STOP COMMANDS
.SKIP 5

     This section describes the various physical tab stop commands which
are included within the CRT driver.  These commands enable a user to
clear, set, and jump to horizontal and vertical physical tab stops 
on the user terminal.
.PAGE
.HEADER LEVEL 2 HORIZONTAL TAB STOP COMMANDS
.INDEX <CRT__SET__TAB
.HEADER LEVEL 3 CRT__SET__TAB

     This entrypoint sets a horizontal physical tab at the 
current cursor column
position.  This tab stop stays in effect until a RESET or CLEAR__TAB
command is executed.
.INDEX <CRT__CLEAR__TAB
.HEADER LEVEL 3 CRT__CLEAR__TAB

     This entrypoint clears a horizontal physical tab at 
the current cursor column
position.  This command has no effect if there is no tab stop at the
current cursor column position. 
.INDEX <CRT__CLEAR__TABS
.HEADER LEVEL 3 CRT__CLEAR__TABS

     This entrypoint clears all horizontal physical tab 
stops for the current user
terminal.  Tab stops resident in the non-volatile memory of the terminal
will reappear upon a RESET or power down condition.
.INDEX <CRT__TAB
.HEADER LEVEL 3 CRT__TAB

     This entrypoint forces the user terminal to jump to the next
horizontal physical tab stop by issuing a TAB character to the terminal.
.PAGE
.HEADER LEVEL 2 VERTICAL TAB STOP (VFU) COMMANDS
.INDEX <CRT__SET__VFU
.HEADER LEVEL 3 CRT__SET__VFU

     This entrypoint sets a vertical forms unit (VFU) physical tab at
the current cursor row (line) position.  This VFU tab stop stays in
effect until a RESET or CLEAR__TAB command is executed.
.INDEX <CRT__CLEAR__VFU
.HEADER LEVEL 3 CRT__CLEAR__VFU

     This entrypoint clears a vertical forms unit (VFU) physical tab at
the current cursor row (line) position.  This command has no effect if
there is no tab stop at the current cursor row (line) position.
.INDEX <CRT__CLEAR__VFUS
.HEADER LEVEL 3 CRT__CLEAR__VFUS

     This entrypoint clears all vertical forms unit (VFU) physical tabs 
for the current user terminal.  Tab stops resident in the non-volatile
memory of the terminal will reappear upon a RESET or power down condition.
.INDEX <CRT__VFU
.HEADER LEVEL 3 CRT__VFU

     This entrypoint forces the user terminal to jump to the next 
vertical forms unit (VFU) physical tab stop by issuing a vertical tab
(VT) character to the terminal.
.COMMENT****************************************************************
.COMMENT     HORIZONTAL AND VERTICAL CHARACTER PITCH                   *
.COMMENT****************************************************************
.PAGE
.HEADER LEVEL 1 HORIZONTAL AND VERTICAL PITCH COMMANDS
.SKIP 5

     This section describes the various horizontal and vertical
line size, character width, and
character height commands which are included within the CRT driver.
It should be noted that most of the commands within this section
are device specific in nature, but that as much as possible the 
high level commands have been standardized to make the interface
as uniform and device independent as possible.
.PAGE
.INDEX <CRT__HORIZONTAL
.HEADER LEVEL 2 CRT__HORIZONTAL(PITCH)

     This entrypoint changes the current horizontal pitch of the given
terminal to PITCH characters/inch.  This entrypoint has more 
significance for hardcopy units than for CRT displays, but it is
supported for both devices.

     Currently supported horizontal pitch values for the LA120 hardcopy
terminal are:  5, 6, 7, 8, 10, 12, 13, and 16 characters/inch. Values
not specified here are defaulted to the closest possible value listed.
Negative values are reserved for future expansion.
.INDEX <CRT__VERTICAL
.HEADER LEVEL 2 CRT__VERTICAL(PITCH)

     This entrypoint changes the current vertical pitch of the given
terminal to PITCH lines/inch.  This entrypoint has more significance
for hardcopy units than for CRT displays, but it is supported for 
both devices. 

     Currently supported vertical pitch values for the LA120 hardcopy
terminal are:  2, 3, 4, 6, 8, and 12 lines/inch.  Values not specified
here are defaulted to the closest possible value listed.
Negative values are reserved for future expansion.
.INDEX <CRT__DOUBLE__TOP
.HEADER LEVEL 2 CRT__DOUBLE__TOP

     This entrypoint changes the current line to double-height top half
for VT100 and DT80/1 terminals.
.INDEX <CRT__DOUBLE__BOT
.HEADER LEVEL 2 CRT__DOUBLE__BOT

     This entrypoint changes the current line to double-height bottom
half for VT100 and DT80/1 terminals.
.INDEX <CRT__SINGLE__WIDE
.HEADER LEVEL 2 CRT__SINGLE__WIDE

     This entrypoint changes the current line to single-width single-height
for VT100 and DT80/1 terminals.
.INDEX <CRT__DOUBLE__WIDE
.HEADER LEVEL 2 CRT__DOUBLE__WIDE

     This entrypoint changes the current line to double-width single-height
for VT100 and DT80/1 terminals.
.COMMENT****************************************************************
.COMMENT     CHARACTER ATTRIBUTE COMMANDS                              *
.COMMENT****************************************************************
.PAGE
.HEADER LEVEL 1 CHARACTER ATTRIBUTE COMMANDS
.SKIP 5

     This section describes the various character attribute commands
which are included within the CRT driver.  It should be noted that 
all of the entrypoints which reference color enhancements are 
nonfunctional except for terminals having color graphics capability.
.PAGE
.INDEX <CRT__TURN__OFF
.HEADER LEVEL 2 CRT__TURN__OFF

     This entrypoint disables all character attributes and places
the terminal in a white character on black background mode.  This
also takes a color graphics terminal out of any color mode and
places it in this standard display mode.
.INDEX <CRT__BOLD
.HEADER LEVEL 2 CRT__BOLD

     This entrypoint enables the BOLD character attribute if it is 
defined on the current terminal.  This makes characters/background
appear brighter or more enhanced than in normal display mode.
.INDEX <CRT__UNDER
.HEADER LEVEL 2 CRT__UNDER

     This entrypoint enables the UNDERSCORE character attribute if it
is defined on the current terminal.  This makes all characters displayed
from that point on have an underscore associated with them.
.INDEX <CRT__BLINK
.HEADER LEVEL 2 CRT__BLINK

     This entrypoint enables the BLINK character attribute if it is
defined on the current terminal.  This makes all characters displayed
from that point on blink on and off.
.INDEX <CRT__REVERSE
.HEADER LEVEL 2 CRT__REVERSE

     This entrypoint enables the REVERSE VIDEO character attribute if it is
defined on the current terminal.  This makes the background and foreground
color definitions to switch for the characters displayed from that point
on.
.PAGE
.HEADER LEVEL 2 COLOR SELECTION COMMANDS
.SKIP 5

     This section describes the color character attribute commands
which are included within the CRT driver.  Currently the only
color terminal supported by the CRT driver is the ISC 8001, but this
will definitely change in the near future.  It is for this reason
that this color interface is still in a state of design review at
present.  The final design will include the raw color commands
plus an additional high level graphics interface yet to be defined.
Note that color commands directed to a black and white
terminal or hardcopy device will be ignored.
.PAGE
.INDEX <CRT__COLOR
.HEADER LEVEL 3 CRT__COLOR(COLOR__MASK)

     This entrypoint sets the current active color in either the foreground
or background area, depending whether the user has selected the REVERSE
VIDEO character attribute.  The COLOR__MASK argument determines the
color to be selected as the new active foreground or background color.
Symbolic offsets for this color definition have yet to be standardized,
thus this entrypoint is included for future expansion only at this
point.
.INDEX <CRT__HUE__BLACK
.HEADER LEVEL 3 CRT__HUE__BLACK

     This entrypoint sets the current active color to BLACK.  This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__RED
.HEADER LEVEL 3 CRT__HUE__RED

     This entrypoint sets the current active color to RED.  This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__GREEN
.HEADER LEVEL 3 CRT__HUE__GREEN

     This entrypoint sets the current active color to GREEN.  This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__YELLOW
.HEADER LEVEL 3 CRT__HUE__YELLOW

     This entrypoint sets the current active color to YELLOW.  This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__BLUE
.HEADER LEVEL 3 CRT__HUE__BLUE

     This entrypoint sets the current active color to BLUE.  This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__MAGENTA
.HEADER LEVEL 3 CRT__HUE__MAGENTA

     This entrypoint sets the current active color to MAGENTA.  This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__CYAN
.HEADER LEVEL 3 CRT__HUE__CYAN

     This entrypoint sets the current active color to CYAN. This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.INDEX <CRT__HUE__WHITE
.HEADER LEVEL 3 CRT__HUE__WHITE

     This entrypoint sets the current active color to WHITE. This will
modify the display foreground/background depending on the previous
state of the REVERSE VIDEO character attribute.
.COMMENT****************************************************************
.COMMENT     ERASING COMMANDS                                          *
.COMMENT****************************************************************
.PAGE
.HEADER LEVEL 1 ERASING COMMANDS
.SKIP 5

     This section describes the various screen erasing commands which
are included within the CRT driver.  It should be noted that whenever
possible, all the screen erasing commands are simulated on terminals
with less functionality, but that in some cases the terminal erasing
function cannot be simulated exactly.  Users should be aware of this
restriction when writing code for pre-ANSI terminals.
.PAGE
.INDEX <CRT__CLEAR__EOL
.HEADER LEVEL 2 CRT__CLEAR__EOL

     This entrypoint erases the screen from the current cursor
position to the end of 
the current display line (EOL).  Cursor positon is not changed.
.INDEX <CRT__CLEAR__BOL
.HEADER LEVEL 2 CRT__CLEAR__BOL

     This entrypoint erases the screen from the beginning of the current
display line (BOL) to the current cursor position. Cursor position is
not changed.
.INDEX <CRT__CLEAR__LINE
.HEADER LEVEL 2 CRT__CLEAR__LINE

     This entrypoint erases the entire line on which the cursor is
positioned.  Cursor position is not changed.
.INDEX <CRT__CLEAR__BOP
.HEADER LEVEL 2 CRT__CLEAR__BOP

     This entrypoint erases the screen from the beginning of the current
display screen (BOP) to the current cursor position.  Curson position
is not changed.
.INDEX <CRT__CLEAR__EOP
.HEADER LEVEL 2 CRT__CLEAR__EOP

     This entrypoint erases the screen from the current cursor position
to the end of the current display screen (EOP). Cursor positon is not
changed.
.INDEX <CRT__CLEAR__PAGE
.HEADER LEVEL 2 CRT__CLEAR__PAGE

     This entrypoint erases the entire screen on which the cursor is
positoned.  Cursor position is not changed.
.COMMENT****************************************************************
.COMMENT     SPECIAL DISPLAY FUNCTIONS                                 *
.COMMENT****************************************************************
.PAGE
.HEADER LEVEL 1 SPECIAL DISPLAY COMMANDS
.SKIP 5

     This section describes the various special display commands which
are included within the CRT driver.  It should be noted that these
special display commands are purely device specific and are not
represented on a broad number of the terminals supported by the CRT
driver.
.PAGE
.INDEX <CRT__CLEAR__LEDS
.HEADER LEVEL 2 CRT__CLEAR__LEDS

     This entrypoint turns off the 4 LED display indicators (L1, L2, L3, and
L4) which are present on VT100 and DT80/1 terminals.
.INDEX <CRT__SET__LED
.HEADER LEVEL 2 CRT__SET__LED(LED)

     This entrypoint turns on a specific LED display indicator (L1, L2,
L3, or L4) based on the passed 'LED' argument. A value of 0 turns off all
LEDs, and values 1 through 4 correspond to the led indicators L1 through
L4.
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     CHARACTER SET SELECTION COMMANDS                          *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER CHARACTER SET SELECTION COMMANDS
.DISPLAY CHAPTER
.PAGE

     This chapter describes the various character set selection
and control functions performed by the CRT driver.  These character
set selection commands enable the user to dynamically select and
deselect a variety of character sets based on what is available 
through the hardware of the current user terminal.
.PAGE
.HEADER LEVEL 1 STANDARD CHARACTER SET COMMANDS
.SKIP 5

     This section describes the various standard character set
selection commands which are available within the CRT driver.
It should be noted that many terminals will not support alternate
character set selection commands.  These commands will be ignored
in such cases.
.PAGE
.INDEX USASCII
.HEADER LEVEL 2 USASCII
.SKIP 5

     The following entrypoint descriptions deal with selection of 
United States ASCII character sets (USASCII).  USASCII is defined
as the standard default character set of the CRT driver.
.INDEX <CRT__USASCII
.INDEX <CRT__USASCII__G0
.HEADER LEVEL 3 CRT__USASCII, CRT__USASCII__G0

     Selects the USASCII G0 designator character set.
.INDEX <CRT__USASCII__G1
.HEADER LEVEL 3 CRT__USASCII__G1

     Selects the USASCII G1 designator character set.
.PAGE
.HEADER LEVEL 2 UNITED KINGDOM (UK)
.SKIP 5

     The following entrypoint descriptions deal with selection of
United Kingdom character sets (UK). The UK character set differs
from the USASCII character set in that the pound sign ('_#') has
a different graphic designator in the UK character set ('L').
.INDEX <CRT__UK
.INDEX <CRT__UK__G0
.HEADER LEVEL 3 CRT__UK, CRT__UK__G0

     Selects the UK G0 designator character set.
.INDEX <CRT__UK__G1
.HEADER LEVEL 3 CRT__UK__G1

     Selects the UK G1 designator character set.
.PAGE
.INDEX GRAPHICS
.HEADER LEVEL 2 GRAPHICS LINE DRAWING
.SKIP 5

     The following entrypoint descriptions deal with selection of
graphics line drawing character sets.  These character sets enable
the user to display rectangles, forms, and other stick figures using
special line drawing and graphic symbol characters.  When this mode
is enabled, the CRT driver graphic symbol entrypoints (CRT__SYM__)
are enabled and will display the desired graphic symbol when properly
called by the user program. See SPECIAL GRAPHICS SYMBOLS for further
information.
.INDEX <CRT__GRAPHICS
.INDEX <CRT__GRAPHICS__G0
.HEADER LEVEL 3 CRT__GRAPHICS, CRT__GRAPHICS__G0

     Selects the graphics line drawing G0 designator character set.
Enables CRT driver graphics symbol entrypoints.
.INDEX <CRT__GRAPHICS__G1
.HEADER LEVEL 3 CRT__GRAPHICS__G1

     Selects the graphics line drawing G1 designator character set.
Enables CRT driver graphics symbol entrypoints.
.PAGE
.HEADER LEVEL 1 NONSTANDARD CHARACTER SET COMMANDS
.SKIP 5

     This section describes the various nonstandard character set 
selection commands which are included within the CRT driver.  These
character set selection commands have yet to be fully defined within
the Mostek CRT driver standard, and should therfore be 
considered reserved for future expansion.
.PAGE
.HEADER LEVEL 2 ROM1 CHARACTER SET
.SKIP 5

     The following entrypoint descriptions deal with selection of
characters within the alternate character ROM1.  These characters
have yet to be defined within this standard.
.INDEX <CRT__ROM1
.INDEX <CRT__ROM1__G0
.HEADER LEVEL 3 CRT__ROM1, CRT__ROM1__G0

     Selects the alternate character ROM1 G0 designator character set.
.INDEX <CRT__ROM1__G1
.HEADER LEVEL 3 CRT__ROM1__G1

     Selects the alternate character ROM1 G1 designator character set.
.PAGE
.HEADER LEVEL 2 ROM2 CHARACTER SET
.SKIP 5

     The following entrypoint descriptions deal with selection of
characters within the alternate character ROM2 special graphics 
character set.  These characters have yet to be defined within this
standard.
.INDEX <CRT__ROM2
.INDEX <CRT__ROM2__G0
.HEADER LEVEL 3 CRT__ROM2, CRT__ROM2__G0

     Selects the alternate character ROM2 G0 designator character set.
.INDEX <CRT__ROM2__G1
.HEADER LEVEL 3 CRT__ROM2__G1

     Selects the alternate character ROM2 G1 designator character set.
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     SPECIAL GRAPHICS SYMBOLS                                  *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER SPECIAL GRAPHICS SYMBOLS
.DISPLAY CHAPTER
.PAGE

     This chapter describes the various special graphics symbols
which are available through single calls to the CRT driver.
Most of the symbols are device specific to the VT100 and DT80/1
terminals, but some are available on the other supported terminals.
Note that all graphics symbol entrypoints begin with the common
designator 'CRT__SYM__' to designate them as graphic symbol entrypoints.

.NOTE WARNING
The user must have enabled the special GRAPHICS character set
mode with a call to CRT__GRAPHICS
before attempting to use these alternate graphics characters.
Reference CHARACTER SET SELECTION COMMANDS for character set selection
procedures.
.END NOTE
.PAGE
.HEADER LEVEL 1 STANDARD GRAPHICS CHARACTERS
.SKIP 5

     This section describes the various standard graphics character
entrypoints which are included within the CRT driver.  It should be 
noted that this standard set is all that is actively supported at
present
.PAGE
.INDEX <CRT__SYM__BLANK
.HEADER LEVEL 2 CRT__SYM__BLANK

     This entrypoint displays a blank character at the current cursor
position.
.INDEX <CRT__SYM__DIAMOND
.HEADER LEVEL 2 CRT__SYM__DIAMOND

     This entrypoint displays a diamond symbol at the current cursor
positon.
.INDEX <CRT__SYM__CHECK
.HEADER LEVEL 2 CRT__SYM__CHECK

     This entrypoint displays a check board (error indicator) symbol
at the current cursor position.
.INDEX <CRT__SYM__HT
.HEADER LEVEL 2 CRT__SYM__HT

     This entrypoint displays a HT (horizontal tab) symbol at the current
cursor position.
.INDEX <CRT__SYM__FF
.HEADER LEVEL 2 CRT__SYM__FF

     This entrypoint displays a FF (form feed) symbol at the current
cursor position.
.INDEX <CRT__SYM__CR
.HEADER LEVEL 2 CRT__SYM__CR

     This entrypoint displays a CR (carriage return) symbol at the
current cursor positon.
.INDEX <CRT__SYM__LF
.HEADER LEVEL 2 CRT__SYM__LF

     This entrypoint displays a LF (line feed) symbol at the current
cursor position.
.INDEX <CRT__SYM__DEGREE
.HEADER LEVEL 2 CRT__SYM__DEGREE

     This entrypoint displays a degree symbol at the current cursor
position
.INDEX <CRT__SYM__PL__MIN
.HEADER LEVEL 2 CRT__SYM__PL__MIN

     This entrypoint displays a plus/minus (+/-) symbol at the current
cursor position
.INDEX <CRT__SYM__NL
.HEADER LEVEL 2 CRT__SYM__NL

     This entrypoint displays a NL (new line) symbol at the current 
cursor position.
.INDEX <CRT__SYM__VT
.HEADER LEVEL 2 CRT__SYM__VT

     This entrypoint displays a VT (vertical tab) symbol at the current
cursor position.
.INDEX <CRT__SYM__LRC
.HEADER LEVEL 2 CRT__SYM__LRC

     This entrypoint displays a lower-right corner symbol at the current
cursor position. Used to draw rectangle corners.
.INDEX <CRT__SYM__URC
.HEADER LEVEL 2 CRT__SYM__URC

     This entrypoint displays an upper-right corner symbol at the current
cursor position. Used to draw rectangle corners.
.INDEX <CRT__SYM__ULC
.HEADER LEVEL 2 CRT__SYM__ULC

     This entrypoint displays an upper-left corner symbol at the current
cursor position. Used to draw rectangle corners.
.INDEX <CRT__SYM__LLC
.HEADER LEVEL 2 CRT__SYM__LLC

     This entrypoint displays a lower-left corner symbol at the current 
cursor position.  Used to draw rectangle corners.
.INDEX <CRT__SYM__CROSS
.HEADER LEVEL 2 CRT__SYM__CROSS

     This entrypoint displays a crossing line symbol at the current 
cursor position.  This symbol is a vertical bar with a horizontal
line centered at SCAN line 5. 
.INDEX <CRT__SYM__SCAN1
.HEADER LEVEL 2 CRT__SYM__SCAN1

     This entrypoint displays a horizontal scan line 1 symbol at the
current cursor position.
.INDEX <CRT__SYM__SCAN3
.HEADER LEVEL 2 CRT__SYM__SCAN3

     This entrypoint displays a horizontal scan line 3 symbol at the 
current cursor position.
.INDEX <CRT__SYM__SCAN5
.HEADER LEVEL 2 CRT__SYM__SCAN5

     This entrypoint displays a horizontal scan line 5 symbol at the
current cursor position.
.INDEX <CRT__SYM__SCAN7
.HEADER LEVEL 2 CRT__SYM__SCAN7

     This entrypoint displays a horizontal scan line 7 symbol at the
current cursor position.
.INDEX <CRT__SYM__SCAN9
.HEADER LEVEL 2 CRT__SYM__SCAN9

     This entrypoint displays a horizontal scan line 9 symbol at the
current cursor position.
.INDEX <CRT__SYM__LEFT__T
.HEADER LEVEL 2 CRT__SYM__LEFT__T

     This entrypoint displays a left "T" symbol at the current 
cursor position.  Used to draw internal rectangles.
.INDEX <CRT__SYM__RIGHT__T
.HEADER LEVEL 2 CRT__SYM__RIGHT__T

     This entrypoint displays a right "T" symbol at the current
cursor position.  Used to draw internal rectangles.
.INDEX <CRT__SYM__LOWER__T
.HEADER LEVEL 2 CRT__SYM__LOWER__T

     This entrypoint displays a bottom (lower) "T" symbol at the current
cursor position.  Used to draw internal rectangles.
.INDEX <CRT__SYM__UPPER__T
.HEADER LEVEL 2 CRT__SYM__UPPER__T

     This entrypoint displays an top (upper) "T" symbol at the current
cursor position.  Used to draw internal rectangles.
.INDEX <CRT__SYM__V__BAR
.HEADER LEVEL 2 CRT__SYM__V__BAR

     This entrypoint displays a vertical bar symbol at the current
cursor position.  Used to draw rectangles.
.INDEX <CRT__SYM__V__LINE
.HEADER LEVEL 2 CRT__SYM__V__LINE(COUNT)

     This entrypoint displays a vertical line 'COUNT' lines long
using the vertical bar symbol.  Used to draw rectangles.
.INDEX <CRT__SYM__LE
.HEADER LEVEL 2 CRT__SYM__LE

     This entrypoint displays a less-than-or-equal-to symbol
at the current cursor position.
.INDEX <CRT__SYM__GE
.HEADER LEVEL 2 CRT__SYM__GE

     This entrypoint displays a greater-than-or-equal-to symbol at
the current cursor position.
.INDEX <CRT__SYM__PI
.HEADER LEVEL 2 CRT__SYM__PI

     This entrypoint displays the PI (mathematical) symbol at the
current cursor position.
.INDEX <CRT__SYM__NE
.HEADER LEVEL 2 CRT__SYM__NE

     This entrypoint displays the NE (not equal to) symbol at the
current cursor position.
.INDEX <CRT__SYM__POUND
.HEADER LEVEL 2 CRT__SYM__POUND

     This entrypoint displays the UK pound sign symbol at the current
cursor position.
.INDEX <CRT__SYM__DOT
.HEADER LEVEL 2 CRT__SYM__DOT

     This entrypoint displays a centered dot symbol at the current
cursor position.
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     GRAPHICS PLOTTING COMMANDS                                *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER GRAPHICS PLOTTING COMMANDS
.DISPLAY CHAPTER
.PAGE
.SKIP 5

     This chapter describes the various graphics plotting functions
performed by the CRT driver.  These plotting functions enable a user
to rapidly and efficiently generate semi-graphic or graphic plots on
the display surface, and in addition provide a hardware transparent
method of producing software for this purpose.

     The user should note that the origin for all plotted data is (1,1)
and is located at the lower-left hand corner of the display surface.
The maximum plotting coordinates are determined by the specific terminal
to be used.  Future enhancements of the CRT driver will enable the
user to query the specific plotting limits for the specified terminal.

.NOTE WARNING
The user must have enabled the special graphics character set mode with
a call to CRT__GRAPHICS before attempting to use these graphics plotting
commands.  Reference CHARACTER SET SELECTION COMMANDS for further 
information regarding character set selection procedures.
.END NOTE
.PAGE
.HEADER LEVEL 1 BASIC PLOTTING FUNCTIONS
.SKIP 5

     This section describes the basic graphics plotting functions
which are included within the CRT driver.  These plotting functions
will be emulated to the extent that is possible on the various
terminals supported by the CRT driver.
.PAGE
.INDEX <CRT__PLOT
.HEADER LEVEL 2 CRT__PLOT(X,Y)

     This entrypoint enables the specified raster point on the XY
plotting surface.  The specific limits of the plotting surface are
dependent on the type of terminal used.  At present no method exists
by which a user may interrogate the plotting limits of the current
terminal configuration.  This restriction will be eliminated in
future releases of the CRT driver.
.PAGE
.HEADER LEVEL 1 ADVANCED PLOTTING FUNCTIONS
.SKIP 5

     This section describes the various advanced graphics plotting
commands which are included within the CRT driver.  These graphics
plotting commands are currently only supported on the terminals
which support advanced graphics features.  Support for lower-level
terminals will be provided in a later release of the CRT driver.
.PAGE
.INDEX <CRT__PLOT__X__BAR
.HEADER LEVEL 2 CRT__PLOT__X__BAR(X__START,Y__START,X__LIMIT)

     This entrypoint enables the user to display a horizontal bar 
graph of length X__LIMIT in the right-hand direction from a starting
coordinate of (X__START,Y__START).  The current foreground color is used
in constructing the bar graph.
.INDEX <CRT__PLOT__Y__BAR
.HEADER LEVEL 2 CRT__PLOT__Y__BAR(X__START,Y__START,Y__LIMIT)

     This entrypoint enables the user to display a vertical bar
graph of length Y__LIMIT in the bottom-up direction from a starting
coordinate of (X__START,Y__START).  The current foreground color is used
in constructing the bar graph.
.INDEX <CRT__PLOT__VECTOR
.HEADER LEVEL 2 CRT__PLOT__VECTOR(X__STOP,Y__STOP)

     This entrypoint enables the user to display a vector from the last
displayed point to a new point of (X__STOP,Y__STOP).  The last displayed
point is obtained from the last call to the CRT__PLOT command or the
last call to the CRT__PLOT__VECTOR command. The current foreground color
is used in constructing the vector.
.INDEX <CRT__PLOT__LINE
.HEADER LEVEL 2 CRT__PLOT__LINE(X__START,Y__START,X__STOP,Y__STOP)

     This entrypoint enables the user to display a line vector from 
a starting point of (X__START,Y__START) to an ending point of
(X__STOP,Y__STOP).  The current foreground color is used in
constructing the line vector.
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     TERMINAL MODE CONVERSION COMMANDS                         *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER TERMINAL MODE CONVERSION COMMANDS
.DISPLAY CHAPTER
.PAGE

     This chapter describes the various terminal mode conversion
commands performed by the CRT driver.  These mode conversion
commands change basic characteristics in the user terminal.
Most of these entrypoints are VT100/DT80 specific.
.PAGE
.HEADER LEVEL 1 STANDARD MODE CONVERSION COMMANDS
.SKIP 5

     This section describes the standard mode conversion commands
which are included within the CRT driver.  It should be noted
that most of the following mode conversion commands are device
specific to the VT100/DT80 terminals.
.PAGE
.HEADER LEVEL 2 LINE MODES
.SKIP 5
.INDEX <CRT__NL__MODE
.INDEX <CRT__LF__MODE
.HEADER LEVEL 3 CRT__NL__MODE

     This entrypoint enables new line mode.  If new line mode is
enabled, a carriage return received by the user terminal will be
interpreted as a carriage return and a line feed.
Complement to the CRT__LF__MODE entrypoint.
.HEADER LEVEL 3 CRT__LF__MODE

     This entrypoint enables line feed mode. If line feed mode is
enabled, a carriage return received by the user terminal will be
interpreted as a carriage return only.  Complement to the CRT__NL__MODE
entrypoint.
.PAGE
.HEADER LEVEL 2 CURSOR KEYPAD MODES
.SKIP 5
.INDEX <CRT__CURSOR__APP
.INDEX <CRT__CURSOR__KEY
.HEADER LEVEL 3 CRT__CURSOR__APP

     This entrypoint enables cursor application keypad mode.  This
forces the user terminal to associate the application keypad character
set with the cursor position keys.  Complement to the CRT__CURSOR__KEY
entrypoint.
.HEADER LEVEL 3 CRT__CURSOR__KEY

     This entrypoint enables cursor key keypad mode.  This forces
the user terminal to associate the cursor key character set with the
cursor position keys.  Complement to the CRT__CURSOR__APP entrypoint.
.PAGE
.HEADER LEVEL 2 NUMERIC KEYPAD MODES
.SKIP 5
.INDEX <CRT__KEYPAD__APP
.INDEX <CRT__KEYPAD__NUM
.HEADER LEVEL 3 CRT__KEYPAD__APP

     This entrypoint enables auxiliary keypad application keypad mode.
This forces the user terminal to associate the application keypad
character set with the auxiliary numeric keypad keys.  Complement to the
CRT__KEYPAD__NUM entrypoint.
.HEADER LEVEL 3 CRT__KEYPAD__NUM

     This entrypoint enables auxiliary keypad numeric keypad mode.
This forces the user terminal to associate the numeric keypad 
character set with the auxiliary numeric keypad keys.  Complement to the
CRT__KEYPAD__APP entrypoint.  Keypad numeric mode is the normal
power-up state of the terminal.
.PAGE
.HEADER LEVEL 2 TERMINAL EMULATION MODES
.SKIP 5
.INDEX <CRT__ANSI
.INDEX <CRT__VT100
.INDEX <CRT__VT52
.INDEX <CRT__ISC__8001
.HEADER LEVEL 3 CRT__ANSI, CRT__VT100

     This entrypoint enables ANSI mode escape sequence recognition.
This forces the user terminal to emulate ANSI standards with respect
to interpretation of received escape sequences.  Complement to the
CRT__VT52 entrypoint.
.HEADER LEVEL 3 CRT__VT52

     This entrypoint enables VT52 mode escape sequence recognition.
This forces the user terminal to emulate DEC VT52 standards with
respect to interpretation of received escape sequences.  Complement to
the CRT__ANSI entrypoint.  This entrypoint is included for symetry
only - it is not compatible with the overall philosophy and structure
of the CRT driver.
.HEADER LEVEL 3 CRT__ISC__8001

     This entrypoint enables ISC__8001 mode control sequence recognition.
This forces the user terminal to emulate ISC 8001 standards with
respect to interpretation of received control sequences.  Complement to
the CRT__ANSI entrypoint.  This entrypoint is included for symetry
only - it s not compatible with the overall philosophy and structure
of the CRT driver.
.PAGE
.HEADER LEVEL 2 LINE WIDTH MODES
.SKIP 5
.INDEX <CRT__132__COLUMN
.INDEX <CRT__80__COLUMN
.HEADER LEVEL 3 CRT__132__COLUMN

     This entrypoint enables 132 column mode for terminals
which support this feature.  In this mode, 132 columns are displayed
in compressed format on a single line.  The display is blanked and
the cursor homed after execution of this mode conversion command.
Complement to the CRT__80__COLUMN entrypoint.
.HEADER LEVEL 3 CRT__80__COLUMN

     This entrypoint enables 80 column mode for terminals
which support this feature.  In this mode, 80 columns are displayed
in normal format on a single line. The display is blanked and the
cursor homed after execution of this mode conversion command.
Complement to the CRT__132__COLUMN entrypoint.
.PAGE
.HEADER LEVEL 2 SCROLLING MODES
.SKIP 5
.INDEX <CRT__SMOOTH
.INDEX <CRT__JUMP
.HEADER LEVEL 3 CRT__SMOOTH

     This entrypoint enables smooth scrolling mode for terminals
which support this feature.  In this mode when the display is indexed
up or down, the user terminal does so in a smooth fashion at a rate
corresponding to approximately 1200 baud.  Complement to the
CRT__JUMP entrypoint.
.HEADER LEVEL 3 CRT__JUMP

     This entrypoint enables jump scrolling mode for terminals
which support this feature.  In this mode when the display is indexed
up or down, the user terminal does so in the normal fashion (one line
at an instant).  Complement to the CRT__SMOOTH entrypoint.
.PAGE
.HEADER LEVEL 2 SCREEN MODES
.SKIP 5
.INDEX <CRT__PAGE__LIGHT
.INDEX <CRT__PAGE__DARK
.HEADER LEVEL 3 CRT__PAGE__LIGHT

     This entrypoint enables reverse video on a screen-wide basis
for terminals which support this feature,
forcing black characters on a white background to be the standard
character attribute for the entire page.  Complement to the
CRT__PAGE__DARK entrypoint.
.HEADER LEVEL 3 CRT__PAGE__DARK

     This entrypoint disables reverse video on a screen-wide basis
for terminals which support this feature,
forcing white characters on a black background to be the standard
character attribute for the entire page.  Complement to the
CRT__PAGE__LIGHT entrypoint.
.PAGE
.HEADER LEVEL 2 CURSOR ORIGIN MODES
.SKIP 5
.INDEX <CRT__RELATIVE
.INDEX <CRT__ABSOLUTE
.HEADER LEVEL 3 CRT__RELATIVE

     This entrypoint enables relative cursor addressing on a screen-wide
basis for terminals which support this feature,
forcing the computation of cursor addresses processed by the
CRT__MOVE(ROW,COLUMN) entrypoint to be relative from the current 
cursor position.  Complement to the CRT__ABSOLUTE entrypoint.
.HEADER LEVEL 3 CRT__ABSOLUTE

     This entrypoint enables absolute cursor addressing on a screen-wide
basis for terminals which support this feature,
forcing the computation of cursor addressed processed by the 
CRT__MOVE(ROW,COLUMN) entrypoint to be absolute with respect to the
cursor home (1,1) position at the top left-hand corner of the display
surface.
.PAGE
.HEADER LEVEL 2 LINE WRAP MODES
.SKIP 5
.INDEX <CRT__WRAP__ON
.INDEX <CRT__WRAP__OFF
.HEADER LEVEL 3 CRT__WRAP__ON

     This entrypoint enables wraparound mode on a screen-wide basis,
forcing output lines longer than the current terminal width to be
placed on subsequent rows of the display screen.  Complement to the
CRT__WRAP__OFF entrypoint.
.HEADER LEVEL 3 CRT__WRAP__OFF

     This entrypoint disables wraparound mode on a screen-wide basis,
forcing output lines longer than the current terminal width to 
overwrite the last column position and not to advance to the next
print line on the display screen.
.PAGE
.HEADER LEVEL 2 KEYBOARD REPEAT MODES
.SKIP 5
.INDEX <CRT__REPEAT__ON
.INDEX <CRT__REPEAT__OFF
.HEADER LEVEL 3 CRT__REPEAT__ON

     This entrypoint enables auto-repeat mode for those terminals
which support this feature. In this mode, when a key is depressed
for more than 1 second, it automatically repeats a a rate of 1200
baud.  Complement to the CRT__REPEAT__OFF entrypoint.
.HEADER LEVEL 3 CRT__REPEAT__OFF

     This entrypoint disables auto-repeat mode for those terminals
which support this feature. In this mode, when a key is depressed
no auto-repeat feature is activated and only one character key
depression is processed by the user terminal. Complement to
the CRT__REPEAT__ON entrypoint.
.PAGE
.HEADER LEVEL 2 VIDEO INTERLACE MODES
.SKIP 5
.INDEX <CRT__RETRACE__ON
.INDEX <CRT__RETRACE__OFF
.HEADER LEVEL 3 CRT__RETRACE__ON

     This entrypoint enables video interlace mode for those terminals
which support this feature.  In this mode, the video signal produced
by the terminal and displayed on the screen will be interlaced to 
produce a fuller display with a better graphics rendition.  This mode
is primarily used when displaying graphics data or when using a
video hardcopy device to obtain a line-by-line video dump of the
display screen.  Complement to the CRT__RETRACE__OFF entrypoint.
.HEADER LEVEL 3 CRT__RETRACE__OFF

     This entrypoint disabled video interlace mode for those terminals
which support this feature.  In this mode, the video signal produced
by the terminal and displayed on the screen will not be interlaced.
Complement to the CRT__RETRACE__ON entrypoint.
.PAGE
.HEADER LEVEL 2 GRAPHICS PROCESSOR MODES
.SKIP 5
.INDEX <CRT__GRAPHICS__ON
.INDEX <CRT__GRAPHICS__OFF
.HEADER LEVEL 3 CRT__GRAPHICS__ON

     This entrypoint enables the graphics processor option for those
terminals which support this feature.  The CRT driver does not 
presently support a graphics processor option.  Complement to the
CRT__GRAPHICS__OFF entrypoint.
.HEADER LEVEL 3 CRT__GRAPHICS__OFF
     This entrypoint disables the graphics processor option for those
terminals which support this feature.  The CRT driver does not 
presently support a graphics processor option.  Complement to the
CRT__GRAPHICS__ON entrypoint.
.PAGE
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     AUXILIARY I/O PORT COMMANDS                               *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER AUXILIARY I/O PORT COMMANDS
.DISPLAY CHAPTER
.PAGE

     This chapter describes the various auxiliary I/O port functions
performed by the CRT driver.  These auxiliary I/O port commands
enable the user to transfer data and CRT driver commands to an
auxiliary terminal if the primary terminal is equipped with an
auxiliary terminal interface.  Thus, a DT80 could be the primary 
terminal and have a LA120 connected to its auxiliary I/O port.
This configuration would permit the user to transfer data and
commands both to the DT80 display surface and/or to the LA120
hardcopy unit.  CRT driver commands sent to either unit would
be interpreted according to the characteristics of the terminal
to which they were directed.
.PAGE
.HEADER LEVEL 1 STANDARD I/O PORT COMMANDS
.SKIP 5

     This section describes the various standard I/O port commands 
which are included within the CRT driver. It should be noted that
this standard set is all that is actively supported at present.
.PAGE
.INDEX <CRT__PRINT__PAGE
.HEADER LEVEL 2 CRT__PRINT__PAGE

     This entrypoint forces the primary terminal to transmit the entire
contents of its screen buffer to the auxiliary I/O port interface.
Program control is halted until the "page print" transfer is complete.
.INDEX <CRT__PRINTER__ON
.INDEX <CRT__PRINTER__OFF
.HEADER LEVEL 2 CRT__PRINTER__ON

     This entrypoint forces the primary terminal to enable the 
auxiliary I/O port interface and to direct all further received data
to the auxiliary I/O port without interpretation until a 
PRINTER__OFF command is received.  At this point the primary terminal
is disabled and the auxiliary I/O port is effectively the only
active device as far as the VAX/VMS system is concerned.
Complement to the CRT__PRINTER__OFF entrypoint.
.HEADER LEVEL 2 CRT__PRINTER__OFF

     This entrypoint forces the primary terminal to disable the
auxiliary I/O port interface and to direct all further received
data to the primary display area with interpretation.  Complement
to the CRT__PRINTER__ON entrypoint.
.PAGE
.COMMENT****************************************************************
.COMMENT                                                               *
.COMMENT     DEVICE STATUS REPORT COMMANDS                             *
.COMMENT                                                               *
.COMMENT****************************************************************
.PAGE
.CHAPTER DEVICE STATUS REPORT COMMANDS
.DISPLAY CHAPTER
.PAGE

     This chapter describes the various device status report functions
performed by the CRT driver.  These status report functions enable
the user to query the VAX/VMS operating system as to the present
terminal configuration as well as direct hardware device queries
to the terminal
which will respond with a device-specific response as to its
present configuration.
.PAGE
.HEADER LEVEL 1 SOFTWARE STATUS REPORTS
.SKIP 5
 
     This section describes the various VAX/VMS software status reports
which are available within the CRT driver.  These status reports
enable the user to query/change the current software status of the
current terminal as the VAX/VMS operating system sees the device.
.PAGE
.INDEX <CRT__IO__STATUS
.INDEX <CRT__SENSE__MODE
.INDEX <CRT__SET__MODE
.HEADER LEVEL 2 CRT__IO__STATUS(QUADWORD)
.SKIP 5

     This entrypoint enables the user to obtain the quadword I/O status
buffer of the last I/O operation to the terminal.  This buffer represents
the final I/O completion status of the last operation
and contains additional information
when the CRT__SENSE__MODE and CRT__SET__MODE commands are executed.  Reference
the VAX/VMS I/O USER'S GUIDE for further information as to the specific
contents of the quadword I/O status block returned in argument QUADWORD.

     Please note that ALL entrypoints to the CRT driver return the
status of the last QIO operation as an INTEGER*4 function return value.
Thus a typical user program might include the following statements:
.SKIP 2
.LEFT MARGIN +10
.NOFILL
INTEGER*4 CRT__PRINT
INTEGER*4 STATUS
.SKIP
STATUS=CRT__INITIALIZE
IF (STATUS .NE. %LOC(SS$_NORMAL)) GO TO 900
STATUS=CRT__command(arguments)
IF (STATUS .EQ. %LOC(SS$_DEVCMDERR)) GO TO 900
.LEFT MARGIN -10
.FILL
.SKIP
In this fashion, if the requested CRT driver command fails, the user
can check for this condition and process it accordingly.  Note
that the return status value SS$_DEVCMDERR (device command error)
is returned if the requested CRT driver function is not available
for the current terminal.
.PAGE
.HEADER LEVEL 2 CRT__SENSE__MODE(CLASS,TYPE,PAGWID,PAGLEN,TRMCHR)
.SKIP 5

     This entrypoint returns the current software status of the
terminal line as seen by the VAX/VMS operating system as follows:
.SKIP 2
.LEFT MARGIN +10
CLASS is the device class of the terminal
.SKIP
TYPE is the terminal type mask
.SKIP
PAGWID is the page width of the terminal
.SKIP
PAGLEN is the page length of the terminal
.SKIP
TRMCHR is the terminal characteristics mask
.LEFT MARGIN -10
.SKIP

     Reference the VAX/VMS I/O USER'S GUIDE for further information
on how to interpret the above status fields.
Complement to the CRT__SET__MODE entrypoint.
.PAGE
.INDEX <CRT__TYPEAHEAD
.HEADER LEVEL 2 CRT__TYPEAHEAD(BYTCNT,BYTONE)
.SKIP 5

     This entrypoint enables the user to query the status of the
typeahead buffer associated with the terminal line.  This typeahead
buffer is only active if the terminal line is configured with
the TYPEAHEAD attribute.  The status information returned is as
follows:
.SKIP 2
.LEFT MARGIN +10
BYTCNT is the number of characters currently in the terminal
typeahead buffer
.SKIP
BYTONE is the first character in the typeahead buffer.  This
argument is valid only if BYTCNT > 0.
.LEFT MARGIN -10
.SKIP

     Reference the VAX/VMS I/O USER'S GUIDE for further information
on how to interpret the above status fields.
.PAGE
.HEADER LEVEL 2 CRT__SET__MODE(CLASS,TYPE,PAGWID,PAGLEN,TRMCHR)
.SKIP 5

     This entrypoint sets the current software terminal configuration
of the terminal line as seen by the VAX/VMS operating system as
follows:
.SKIP 2
.LEFT MARGIN +10
CLASS is the device class of the terminal
.SKIP
TYPE is the terminal type mask
.SKIP
PAGWID is the page width of the terminal
.SKIP
PAGLEN is the page length of the terminal
.SKIP
TRMCHR is the terminal characteristics mask
.LEFT MARGIN -10
.SKIP

     Reference the VAX/VMS I/O USER'S GUIDE for further information
on how to interpret the above SET__MODE status fields.  Complement
to the CRT__SENSE__MODE entrypoint.
.PAGE
.INDEX <CRT__ESCAPE__ON
.INDEX <CRT__ESCAPE__OFF
.HEADER LEVEL 2 CRT__ESCAPE__ON

     This entrypoint enables escape control sequence interpretation
and validation for the current terminal line.  This is equivalent
to reading the current terminal characteristics, and then
enabling the TT$M_ESCAPE function modifier for the current terminal 
line.  Useful in providing software support for the cursor key and
application keypad keys, which generate escape sequences when 
properly configured by the CRT__CURSOR__APP and CRT__KEYPAD__APP
entrypoints.  Complement to the CRT__ESCAPE__OFF entrypoint.
.HEADER LEVEL 2 CRT__ESCAPE__OFF

     This entrypoint disables escape control sequence interpretation
and validation for the current terminal line.  This is equivalent
to reading the current teminal characteristica, and then
disabling the TT$M_ESCAPE function modifier for the current terminal
line.  Complement to the CRT__ESCAPE__ON entrypoint.
.PAGE
.HEADER LEVEL 1 DEVICE HARDWARE SPECIFIC STATUS REPORTS

     This section describes the various hardware status report queries
which are available within the CRT driver.  These hardware status
reports are hardware-specific in nature and are therefore not 
supported on most of the devices defined within the CRT driver.
.PAGE
.INDEX <CRT__ANSWERBACK
.HEADER LEVEL 2 CRT__ANSWERBACK

     This entrypoint requests the terminal to transmit its
answerback message to the VAX/VMS operating system which will
then interpret it as a user reply.  It is the duty of the user
to correctly read and interpret this message with one of the
CRT__READ, CRT__POLL, or CRT__INPUT entrypoints.
.PAGE
.DO INDEX
.PRINT INDEX
.PAGE
.CENTER ;End of Manual
.PAGE
.CENTER ;End of Manual