Seven-Bit Graphics - Epson FX-80 User Manual

ABCDEFGHIJKLMNOPQRSTUVWXYZ
ABCDEFGHIJKLMNOPQRSTUVWXYZ
Setting the eighth bit on in line
line 20; thus it prints Italic characters. The ESCape "=" in line 30
effectively subtracts
second line prints as the characters from 65 throught 90. Line 50
returns your system to its usual state.

Seven-bit graphics

The 7-bit limitation affects graphics in two ways. First, 7-bit com-
puter programs are limited in the widths they can specify for graphics.
When you enter a Graphics Mode from a 7-bit system, the first num-
ber (n ) you send can only range as high as 127. Even by changing
1
n from 0 to 1, 2, 3, etc., you can only set specific figure widths: 0 to
2
to 383, 512 to 639, etc.
127, 256
Let's look at an example. The usual way you reserve the entire
width of an 8-inch page for graphics is:
LPRINT CHR$(27)"K"CHR$(224)CHR$(ll);
This gives 224 dots plus 1 times 256 dots, or 480 total. But a 7-bit
system cannot send the 224; the largest number it can send is 127. So
the maximum number attainable with n
which is still less than Single-Density's page width. If you change n
a 0 and n to a 2 you get 0 + 2 x 256 = 512. Now it's too high.
2
So, what can you 7-bit users do? First, do not get discouraged. You
can do a lot in 383 columns of dots and where you really need more
than 383 columns graphics, there is a solution. Just enter Single-Den-
sity Graphics Mode twice on the same line, first for 383 columns and
then for 97 columns.
10 LPRINT CHR$(27)"K"CHR$(127)CHR$(1):
20 FOR X=1 TO 383: LPRINT CHR$(l);: NEXT X
30 LPRINT CHR$(27)"K"CHR$(97)CHR$(0);
40 FOR X=1 TO 97: LPRINT CHR$(l);: NEXT X
50 LPRINT
This gives coverage of the full 480 columns. It's not elegant, but it gets
the job done.
10
from each of the numbers in line 40, so the
128
adds to each of the number in
128
= l is 127 + 1 x 256 = 383,
2
to
1
311