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Defining Your Own Characters
The first step in defining characters is to place the dots on a grid just
as you want them to print. The examples here, like the ones in the
graphics section, use an X to represent each dot. In Figure 6-6 you see a
draft grid with a simple user-defined character planned on it.
Figure 6-6. User-defined character
Now you translate the dot pattern you’ve created on paper to a
numeric format so you can send the information to the LQ. Every dot
has an assigned value. Each vertical column (which has a maximum of
24
dots) is first divided into three groups of eight dots. Each group of
eight dots is represented by one byte, which consists of eight bits.
Hence, one bit represents each dot.
Data numbers
The bits within each byte have values of 1, 2,
4,
8,
16, 32, 64,
and
128. In the vertical column of dots, the bits are arranged so that the
most significant bit (which has a value of 128) is at the top and the least
significant bit (which has a value of
1)
is at the bottom.
Figure 6-7 shows how to use this method to calculate the data num-
bers for the example character. On the left side of the figure the data
numbers are calculated for the middle column. The value of each byte
is calculated by adding the values of the rows where dots appear. The
right side of the figure shows the whole character with the three data
numbers for each column indicated at the bottom.
6-13