Radio Shack TRS-80 Model III - Page 237

APPENDIX
C
/
trs-80
Model
III
Character
Codes
Text is
represented in the
Computer by codes.
For example,
the letter "A" is
represented by the
code 65. Control
functions
and
graphics are also
represented
by codes. The
character codes range
from zero
through 255.
Codes zero
through
31
usually
represent
certain control
functions.
For example,
code 13
represents
a
carriage
return or "end
of line".
However, in
the Model III,
these same codes
also represent
32 special
display
characters. For this
application,
they must be loaded
(POKEd) into video
RAM,
not PRINTed.
Codes 32
through 127
represent the text
characters —
all
those letters,
numbers
and
other characters that are
commonly
used to
represent
textual information. The
Model III text
characters
conform to the
American
National
Standard Code for
Information
Interchange
.
Codes
128
through 191
,
when
output to the
video display,
represent
64
graphics
characters.
Codes 192
through
255,
when output to
the
video display,
represent
either
space
compression codes or
special
characters, as
determined
by
software.
Many of the codes
may be
input from the
keyboard;
all of
them may be
stored in
a
string and output
to any device .
For example ,
to
output
a
code 3
1
to the video
display, use
a
statement like
this:
PRINT CHR$(31)
For
further details, see Using
the Video
Display
in
Section One of this
manual.
Note: In the
following table,
vidram
refers to
Video
RAM,
i.e.
,
addresses
from 15360 to 16383.
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