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External
Program
Mode
On
some
special
wheels,
such
as
OCR-B
10
and
others,
you need
to
"externally" control the
following
(the
box
of
such wheel
shows "Require
Special
Programming").
• Spacing
between
printed character (Proportional space
mode
only)
•
Amount
of ribbon feed
•
Hammer
impression
level
(For ordinary
fonts,
these
are controlled
by
the
program
in
ROM.)
Each
character or
symbol
requires
a different
amount
of
the three factors
above.
First,
you must
enter External
Program
Mode
by sending
control
codes
27,
24
(IB,
18).
Then
send
a
two-byte code
for
each character/symbol.
The
first
byte
is
the
ASCII
code, the
second
byte contains
the data specifying the printing format.
Refer
to
the table
on
Page
19.
For example,
capital letter
"T"
in
OCR-B
font requires 1/10" spacing,
normal
ribbon
feed,
and
level
4 of
hammer
impression.
1/10"
(=
6/60")
is
0110.
Normal
ribbon
feed
is
1.
Level
4 of
hammer
impression
is
100.
Put
together,
we
get
01101100, which
is
108
is
in
decimal,
6C
in
hexadecimal.
By
sending
this
data (108 or
6C),
capital
"T"
is
printed properly
on
OCR-B
10
font.
The
code
for
each character/symbol
is
specified
in
the
code
chart
provided with each wheel.
To
return
to
normal
mode,
send code
27,
25
(IB,
19).
When
you
turn the
power
switch
off
and
then
switch
back
on
again, the Printer
will
be
in
the
normal mode.
Programming
example
To
print
"Tandy"
on
OCR-B
10
print
wheel.
10
LPRINT
CHRS
(27)
CHR$
(24);
'ENTERS
EXTERNAL
PROGRAM MODE
20
LPRINT
CHRS
(84)
CHRS
(108);
'PRINT
CAPITAL
T
30
LPRINT
CHRS
(97)
CHRS
(107);
'PRINT
LOWERCASE A
40
LPRINT
CHRS
(110)
CHRS
(107);
'PRINT
LOWERCASE
N
50
LPRINT
CHRS
(100)
CHRS
(108);
'PRINT
LOWERCASE D
60
LPRINT
CHRS
(121)
CHRS
(107);
'PRINT
LOWERCASE
Y
Note:
That
first
codes of each
program
line
are
ASCII
codes
for
each
character.
Of
course
you
can
program
each
character
inside
quotation
marks
instead
of sending
code
in
ASCII.
For
example,
line
10
can be
10
LPRINT "T"
CHRS
(108);
-
18-
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