APPLICATION NOTE #123
 TESTING WIDTH TABLES IN XYWRITE III AND III PLUS
 Rev. 03


 The PTEST (Printer Test) command lets you test the accuracy of the 
width tables in your printer file. This command is useful when you 
are creating a new printer file or making major changes to an 
existing file.


 COMMAND FORMAT
 The PTEST command has the following basic format:

  PTEST mode,n,start,end

 where mode is the two-letter abbreviation or number associated with a 
XyWrite character display mode (e.g., NM, UL, BO), n is the number of 
the PT (Print Type) table you are testing, start is the value of the 
ASCII character you want to start the test with (the default is 32) 
and end is the value of the ASCII character you want to end the test 
with (the default is 127). The value of end cannot be greater than 
254.

 RUNNING PTEST
 When you run PTEST, XyWrite prints a test file that comprises one 
line for each character in the character set. Each line consists of 
25 repetitions of the character followed by an exclamation point and 
the ASCII value of that character.

 To use PTEST, perform the following steps.

 1.  Call or create the printer file and make the modifications
    you need. For example, to add a new font to an existing
    printer file:

    *  Create a font table that contains definitions and control
       codes for the new fonts. (This information is supplied by
       the printer manufacturer.)

    *  Create a width table using the width information supplied
       by the manufacturer. (If this information is not
       available, see Note #1.)

    *  Create or modify a PT (Print Type) table that defines the
       new font(s).

     Refer to Chapter 6 in the XyWrite Reference Guide for
     information on how to create and modify printer files.

 2.  Store and load the printer file you just modified or created.

 3.  With the screen clear of any file, test the width of one of
    the modes in the new PT table. For example, to test the width
    of normal mode in PT 5:

      Type: F5ptest nm,5<CR>

 4.  Repeat step 3 for each mode and PT table you want to test.

 Result: When the test is successful, the characters print out in 
order, from the narrowest to the widest, and the printed lines 
lengthen accordingly.  If a printed line is followed by a shorter 
line, then there is a width problem. Refer to the documentation 
supplied by your printer manufacturer for width information, and then 
call up your printer file and correct the width table as needed.

 Note #1  Width Information. If you do not have the width information 
for the new font, you can use this method to determine the width of 
each character.

 1.  Define and copy an existing width table. Rename the table to
    reference the new font.

 2.  Run PTEST as described above.

 3.  Calculate the minimum horizontal motion of your printer by
    multiplying the MU (Margin Unit) value found in your printer
    file by 10. (If you have modified this value, use the MU
    defined with the original printer file supplied by XYQUEST.)

 4.  Measure the width of each 25-character line. Don't include
    the exclamation point or the ASCII value in your measurement.

 5.  Divide the measurement taken above by 25 (the number of
    characters on the line) and multiply that number by the
    minimum horizontal motion of your printer (calculated in Step
    3).

 For example, if the width of 25 L's is 2 inches, and your printer 
moves in 300ths of an inch, the following equation calculates the 
width of one L:

    2/25*300=24

 If the result of your calculation is a fraction, you need to convert 
it to a whole number. You can either round it off to the nearest 
whole number, or you can "scale it up." To scale up, you multiply all 
the widths (in every width table in the printer file), as well as the 
MU and DU values, by a common denominator.

 Scaling up produces a more accurate width table than rounding off, 
particularly if many of your widths are fractions. If you choose this 
option, first determine the width of each character in the width 
table (or tables). Then review the result, looking for the common 
denominator.

 For example, if most of the fractions are halves and quarters, the 
common denominator is 4. If most of the fractions are thirds and 
sixths, then the common denominator is 6.

 Remember, you must multiply ALL widths (and the MU and DU values) by 
the common denominator, not just the fractional values.

 Note #2  ASCII 127. ASCII character 127 does not test properly. 
Ignore the results for this character.

 Note #3  Lines/Page. If you are using XyWrite III Plus, Version 3.53, 
the PTEST command has the following form:

      PTEST mode,n,lines,start,end

 The additional argument, lines, defines the number of lines PTEST 
puts on a page. This is useful when you are testing the large points 
sizes available on laser printers.