JP 1000  (260-2960)  Printer Control by the Computer   Faxback Doc. # 3322

THE COMMUNICATION PROTOCOL

One of the most crucial things which affects the correct working of your
printer and computer is the setting of the communication protocol.  If the
protocols do not match, you will not obtain satisfactory results or even
none at all.

It is not difficult to set the protocols correctly, but it is absolutely
necessary that the communication parameters in the printer and in the
computer be compatible.

NOTE:  The information given in this chapter refers to MS-DOS and MS-
       WINDOWS environments as they are the most widely-used.  For other
       environments the same logic remains true, but see the related
       documentation for details.

The indication given here are sufficient for MS-DOS up to release 6.0, and
for MS-WINDOWS up to released 3.1.

Parallel Interface

With the resident parallel interface, you do not have to do anything, as
the only variable parameter is the data format "word length", which, in
the PC, is always set to 8.  This is the printer's default setting.

The parallel communication protocol can be activated using the following
MS-DOS command (consult your MS-DOS manual for the complete syntax):

         MODE LPT1:  (characters per line), (line spacing), P

To address the parallel printer interface as a logical output device, you
can use one of the following names:  LPT1 or PRN.  It is also possible to
redirect output prepared for the parallel interface to a serial interface,
using the command:

         MODE LPT1:=COMn:

Serial Interface

If you install the optional serial interface in your printer, to use it
you must pair up the printer's protocol with the one in your host system
or computer.  The protocol can either be programmed in the printer or you
can adapt your computer to the printer setting using the command:

          MODE COMn: (baud), (parity), (word length), (stop bits), p

where "n" is the number (usually 1) of the addressed interface board, and
baud requires only a two digit number.

PRINTING METHODS

Once your printer and computer are connected correctly and the logical
link established, you can use the printer to its full extent.  If you ran
the print test when you installed the printer, you saw the printer execute
an internally-commanded operation.  You can now have the printer print
something on your command.  The following section contains some basic
operation, which do not require the processing of an application.

NOTE:  For all following operation, make sure the printer is switched on,
       with paper and print head loaded, and that it is ON-LINE.

Printing a Text Screen

The easiest way to obtain a print-out is a screen dump.  Let us presume
you are in your operating system and have made a Directory Listing with
the command DIR.  If you want this list printed out for future reference,
simply press SCR PRT on your PC keyboard (on some PCs, SHIFT is also
required simultaneously).  The printer will start to print everything you
see on the screen exactly as you see it.  You regain the control of your
keyboard when the necessary data transmission to the printer is finished.

This method works from all applications which handle the screen in the
text mode (certain types of graphics may not be printed).

Printing Text Files

The most common printer operation is the printing of a complete text or
data file.  When you have printable files, prepared by your editor, word
processor, database etc., you can send them to print using one of the
following methods.

    A printable file is one which contains only the data to print and
    probably appropriate printer control commands and is basically line
    oriented (closes each printable line with CR/LF).

    When you have the system prompt, type one of the following commands:

    print (filename) - This invokes the print utility of your operating
                       system.  The first time you call it, it will ask
                       you to confirm or change the output port.  For
                       details about file spooling etc., see in your DOS
                       manual.

    NOTE:  This command executes a Form Feed automatically after each
           document is printed.

    type (filename)>prn - This utility normally lists the contents of a
                          file on your screen, but in this case redirects
                          it to the printer, allowing you to interrupt
                          printing with CTRL-C, as you would for the
                          screen.  This command will execute an automatic
                          Form Feed at the end of a document only if it is
                          included in the document itself.

    copy (filename)/B prn - this command also sends the file to the
                            printer.  If you send graphic or DLL (i.e.
                            fonts) files to the printer, remember use the
                            optional "/B" parameter in the command to
                            override any End Of File (=EOF=26D) command,
                            which otherwise would cause DOS to discontinue
                            the data transfer.

    NOTE:  For more detailed information about these commands, consult
           your MS-DOS manual.

SOFTWARE APPLICATIONS

The printer performance can be controlled using software programmers
developed for a wide variety of applications, such as word processor,
spread sheet, data base, graphics, etc.  The software transmits the
operating information to the printer in two different ways, with:

    the driver:  the part of the program which controls the selected
                 printer.

    incorporated commands:  inserted directly in the text to be printed.

INCORPORATED COMMANDS

A printer command code is usually a series of otherwise normally printable
characters inserted in the data string sent to the printer.  To make the
printer understand which characters are to be interpreted as a command and
which as printable characters, there is a simple convention:  all
"characters" that have according to the character table, a decimal value
less than 32 are interpreted received, others do not.

There is also a special command ESCAPE (decimal code 27, names ESC) which
is used by most printer emulations to open a command sequence (also known
as ESCAPE sequences).  It is followed by one or more additional
characters, which serve as identifiers and parameters, belonging to the
range of printable characters or control codes available.

SENDING FILES TO THE PRINTER

When you want to print from a word processor, spread sheet, database,
graphic package or other application, always use the built-in print
function they offer.  Do not attempt to send one of the package's work
files directly to the printer, as they rarely have a format which can be
executed directly by the printer.  They only exception are line oriented
editors.

If you need to print documents independent of the application package, use
the function "print to a file", which some (but not all!) packages offer.
The data written to this file is then exactly like the output otherwise
sent to the printer.  You can now send these files to print from the
operating system level with the commands described already in the section
"Printing Text Files".

When using an application package, the package itself usually takes care
of the correct setting of the page layout parameters, overriding those
defined in SET-UP.  Some packages, however, do not; when using them, check
that all the selectable parameters are compatible, and bear in ind the
following:

    If your printer has a physical TOF and BOF margin, make sure your form
    length definition falls WITHIN these pre-set margins.  If not, you may
    encounter the situation where the printer executes an automatic form
    feed another one just after the start of the next page.

    When defining the line length for your print output, make sure the
    left margin plus the line of text do not exceed physical line length. 
    The amount of printable character per line varies, as it depends on
    the letter size and spacing, but when the print carriage reaches its
    rightmost position and there are some characters left, the printer may
    either ignore the excess characters or automatically print them on the
    following line.  This can destroy your text layout.

(ALL-12/05/94)