Radio Shack TRS-80 model III Owner's Manual page 139

TRS-80
MODEL
III
DISK
SYSTEM
2.
field the buffer, so
you
can
3.
place data into the
buffer
with lset and rset
statements.
When
basic encounters the statement:
PUT
nmexp,nmexp2
it
does the following:
•
Gets
the
information
needed
to
access
the disk
file
•
Checks
the
access
mode
for this
buffer
(must be
r)
•
Acquires
more
disk
space
for the
file if
necessary
to
accommodate
the
record
indicated
by nmexp2
•
Copies the buffer contents into the specified
record of the disk
file
•
Updates
the current
record
number
to
equal
nmexp2
+
1
The "current record"
is
the
record
whose number
is
one higher than
the last
record accessed.
The
first
time
you
access a
file
via a particular buffer, the
current
record
is
set
equal to
1
.
If
the
record
number you
put
is
higher than the end-of-file record
number, then
nmexpl becomes
the
new
end-of-file
record
number.
LSET
and
RSET
Place
Data
in
a
Random
Buffer Field
These two
statements
let
you
place character-string data into fields
previously
set
up by a field statement.
For example, suppose
nm$
and ad$ have been
defined as field
names
for
a
random
file
buffer.
nm$
has a length of 18 characters,
and ad$
has a length of
25
characters,
Now
we
want
to
place
the
following information
into the
buffer
fields
so
it
can
be written to disk:
138