Epson LX-80, Руководство по эксплуатации

Страница: 100 / 193

Figu r e 9-7 is an enlarged representation of the first 14 columns o f the
printou t . In this figure you can see exactly how the printer react ed to
th e fi r s t part of the incorrect program .
128
64
32
16
8
4
2
1
13
13 74 10 13
74
49 10 13 74 10
Figure
9-7.
Pin patterns of incorrect program
Yo u m ay a l s o wonder why the program prints not only the di fferent
pi n patterns but also the character "}" a number of time s. The
reaso n lies i n the number of columns you reserved with the gr aphics
comma nd . After the LX-SOreceives all the numbers reser ve d by a
grap h ics co mmand-50 in this case-it leaves the graphic s mode
and resu m es interpreting numbers as printable characters o r print
co m mands.
S i nce t he i ncorrect program has sent many extra number s, m ainly
10s a n d 13s, the 50 columns reserved are filled before the loop in line
40 h as bee n executed 50 times. Therefore, during the last p asses of
t he l oo p th e LX-SOinterprets CHR$(74) as the ASCII code for " }"
an d prints that character each of the last 35 passes of the l oop .
If you wa nt to make the program work correctly, put th e line-
s p acing co mmand in line 10 , delete line 30 and add two semi- c o lons:
one at t h e e nd of line 20 and one between CHR$(74) and th e colon
in li ne 40.
Th is i n correc t program has been explained in detail so that y ou will
re m em b er two important tips about using the graphics comm and :