Epson LX-80, Operating Manual

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Th e r e ar e four common methods. First, you may be able to bu y a n
a l te r nat i ve printer interface card for your system . This i s th e best
sol ut io n for 7-bit system probl e ms . See your computer d ea l er for
adv i ce a b o ut thi s .
Th e seco nd approach is to use commercially available soft ware that
is s p ecifica ll y designed to overcome these coding problem s. Consult
yo u r co mputer dealer or computer publications to s ee if a pr ogram
for yo u r co mputer system i s a vailable.
T h e t hird a pproach consists of avoiding the software that i s c h anging
t h e codes . On most computers you can send each code dir ectly to
t h e pri nt er port . This bypa s ses the BASIC interpreter a nd avoids
th e i nt e r face.
Unfort un a t e ly , this process is also different for each comput er sys -
t em. So m e of the specific computers mentioned may not b e yours,
bu t t h ey m a y serve as model s to enable you to know wh a t t o do.
Cons u l t yo ur computer manu a l to determine if you can do th e same
on yo u r sys tem .
A fo u r th a pproach is to change th e printer driver progr a m i n your
sys t em. T hi s requires a knowledg e of machine language a nd of the
way yo u r co mputer works . If you don ' t have this knowl e d ge, your
computer d e aler may be abl e to help y ou or sugge s t s om eo n e who
can.
The sa mp le printer driver b e low (following the ex a mpl es of
P OKEi n g co des). The idea is to pass the codes issued b y a B ASIC
p rogra m dire ctl y to the printer .
POKEing codes
T he TR S - 80™ Model I version of the CHR$ function doe s n ot pass
th e va lu es o f 0 , 10 , 11, and 12 onto the printer correctly. Z e r o is a
part i c ul a r problem as it i s very important to the <ESC> codes of
t h e LX-80 printer .
T hese co d es can be sent directly to the printer by POKEing th em to
a spec i a l m e mory location where they are immediately forw a rd ed to
t h e pr int er . The format is:
w h e r e N i s the decimal value of the code you wish to s e nd t o the
p rinte r . Th is works fine as long as the printer is ready to rec e i ve the
d ata w h e n y ou are ready to send it. On the Model
I ,
the prin ter's
r ea d i n ess is a ssured if location 14312 contains a decimal 63 .