Translating Dots To Data; The Attribute Byte - Epson FX-80 User Manual

Translating dots to DATA
The data numbers for each column of Figure 17-2 are calculated just
like those in Graphics Mode. And the appropriate numbers can just as
easily be stored in DATA statements. Type in the READ routine and
data for the character in Figure 17-2:
15~
FOR X=l TO 11: READ C:
LPRINT CHR$(C);: NEXT X
117~
DATA
62,65,8,65,8,65,2B,65,34,~,~:
r
My E
Notice that the DATA statement contains 11 numbers even though the
design uses only 9 of the 11 columns. Unused columns must be coded
as O.
The attribute byte
The attribute byte is the first of the 12 data numbers required to
define any character. At print time it controls two aspects of the way
the character is printed. First, it determines which 8 pins of the print
head are used to print the character. For most characters, the top 8
pins are used, but for lower-case characters with descenders (like g
and p), the bottom 8 pins can be used.
So how does the attribute byte determine which 8 pins are used?
Good question. At print time, the printer checks the attribute byte
before each character is printed. If the high-order bit is on, the top 8
pins of the print head are used; if the high-order bit is off, the bottom 8
are used. To put it another way, if the attribute byte for a given charac-
ter is 128 or greater, the top 8 pins are used; if it is 127 or less, the
bottom 8 are used. Figure 17-4 demonstrates these choices.
199