Radio Shack TRS-80 Trsdos & Disk Basic Reference Manual page 121

DISK BASIC
198
INPUTMODE <L
0,
R)
H
;
MODE*
110 INPUT"BUFFER NUMBER"; BUFFERS
129 INPUT'TILE SPECIFICATION"; FILESPEC*
136 OPEN MODE*,
BUFFER'/.,
FILESPEC*
This
sequence of statements
lets
you
provide the
arguments for the
OPEN
statement during
program
execution.
The
first
character
of
MODES
sets
the access
mode,
BUFFER%
determines
which
buffer
will
be used,
and
FILESPEC
$ gives
the
file
specification.
QPEN ,,
R
M
,
2,
"DATA/BAS.
SPECIAL"
Opens
the
file
DATA/BAS
with password
SPECIAL,
in
the
random
I/O
mode, using buffer
number
2.
If
DATA/BAS
does not
exist,
it
will
be created
on
the
first
non
write-protected drive.
While
a
file is
open,
it is
referenced
by
the
buffer-number
which was
assigned to
it.
Examples:
GET
buffer-number
PUT
buffer-number
PRINT
^buffer-number
INPUT #
b
uffer-n
umber
All
these
statements
will
reference the
file
which was
OPENed
via
buffer-number
.
The
mode
must be
correct.
Once
a
buffer has
been assigned to
a
file
with the
OPEN
statement,
that
buffer
cannot be used
in
another
OPEN
statement.
You
have
to
CLOSE
it
first.
More
on
Buffer
Assignments
Two
or
more
buffers
may
be assigned to the
same
file
for
sequential
input (I-mode).
However, only
one
buffer
at
a
time
may
be assigned
to a
file
for sequential
output
(O-mode)
or
random
access
R-mode.
For example:
10 OPEN
" I
M,
TEST/TXT
:i"
20 OPEN
"
I
",
2, "TEST/TXT
:
1"
Now
TEST/TXT
can be accessed
via
buffers
1
and
2 for sequential
input.
7-35