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The command to enter single-density graphics mode is ESC K nl n2. In
BASIC
the command is given in this format:
LPRINT CHR$(27);"K";CHR$(n1);CHR$(n2);
In this command, ESC K selects single-density graphics, and n1 and n2
specify the number of columns to reserve for graphics.
Column reservation numbers
The graphics command requires more than one number to specify how
many columns to reserve because although one line can use thousands of
columns, the FX does not use numbers larger than 255 (decimal).
Therefore, the graphics mode command uses two numbers for reserving
columns.
To figure nl and n2, divide the total number of columns by 256. The
result is n2; the remainder is nl. Since the command is set up for two
numbers, you must supply two numbers even if you need
only
one.
When you need fewer than 256 columns, just make nl the number of
columns you are reserving and make n2 a zero.
For example, if you wish to send 1632 columns of graphics data, nl
should be 96 and n2 should be 6 because 1632 = 96 + (6 X 256).
Graphics data
After receiving a graphics command such as ESC K nl n2, the printer
prints
the
number of codes specified by nl and n2 as graphics data, no
matter what codes they are. This means that you must be sure to supply
exactly the right amount of graphics data. If you supply too little, the
printer stops and waits for more data and
seems
to be locked. The next
data sent will then be printed as graphics, even if it is really text. On the
other hand, if you supply too much graphics data, the excess will be
printed as regular text.
Graphics programming
Here is an example that shows how a graphics command, column
reservation numbers, and data can be used to print a single line of
graphics. The example is a
BASIC
program. You can, of course, use
another programming language. The principles are the same.
4-12
Using Software and Graphics