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The LQ command to define characters is one of the most complex in
its repertoire. The format of the command is this:
ESCape “&” 0 nl n2 d0 dl d2 data
The ESCape “&" is simple enough. The 0 (which is ASCII code 0,
not the numeral zero in quotation marks) allows for future enhance-
ments. At this time it is always ASCII 0.
With the LQ, you can define many characters with a single com-
mand. The values n1 and n2 are the ASCII codes of the first and last
characters you are defining. If you are defining only one character,
n1
and n2 are the same. You can use any codes between 32 and 127 deci-
mal for
nl
and
n2,
but it is best not to define decimal 32, which is the
code for a space. Also, you can use letters in quotation marks instead
of ASCII numbers for
n1
and
n2.
An example will show how to specify
n1
and
n2.
If, for instance,
you wanted to redefine the characters A through Z,
n1
would be “A”
(or ASCII code 65) and
n2
would be “Z” (or ASCII code 90). So the
command ESCape "&" 0 “AZ” (followed by the appropriate data)
would replace the entire alphabet of capital letters.
Following the specification of the range of characters to be defined
in this command are three data bytes
(d0-d2)
that specify the width of
the character and the space around it. The left space (in dot columns)
is specified by
d0,
and the right space is specified by
d2.
The second
byte
(d1)
specifies the number of columns of dots that are printed to
make up the character. By varying the width of the character itself and
the spaces around it, you can create proportional-width characters
that print at draft speed. Table 6-3 shows the maximum values for
these bytes.
Table 6-3. Character width limits
The last part of the character definition is the actual data that
defines the
dot
patterns for each character. Since it takes three bytes
6-15