Radio Shack TRS-80 Owner's Manual page 52

n:
»EL
ill
DISK
SYSTEM
You may
want
to
use
create
to
prepare
a
file
which
will
contain
a
known
amount
of
data.
This
will usually
speed up
file
write operations. File
reading
will also
be
faster,
since pre-allocated
files are less
segmented
or dispersed
on
the
disk
—
requiring
less
motion
of
the read/write
mechanism
to locate the
records.
Examples
CREATE DATAFILE/BAS (REC=300,
LRL=0)
Creates
a
file
named
datafile/bas, and
allocates space
for
300
256-byte
records.
CREATE NAMES/TXT, IRIS (LRL=64 »REC=50)
Creates
a
file
named
names/txt
protected by
the
password
iris.
The
file
will be
large
enough
to
contain
50
records, each 64
bytes
long.
CREATE PAYROLL/BAS
Creates a
file
named
payroll/bas
but allocates
no
space
to
it.
Sample Use
Suppose you
are
going
to store
personnel information on no more
than 250
employees, and each
data record
will
look
like
this:
Name
(Up
to
25
letters)
Social Security
Number
(11
characters)
Job
Description
(Up
to
92
characters)
Then
your
records
would
need
to be
25
+
1 i
+
92
=
128 bytes
long.
You
could
create an appropriate
file
with
this
command:
CREATE PERSONNL/TXT
(
REC=250
»LRL= 128
Once
created,
this
pre-allocated
file
would
allow
faster writing than would
a
dynamically
allocated
file,
since
trsdos would
not
have
to
stop writing
periodically
to allocate
more
space
(unless
you exceed
the pre-allocated
amount).
DATE
Reset or
Get
Today's
Date
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tor (he
month [mm),
day
\rid]
and
vea?
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W-
36