User`s guide
number
of
the 1541, normally 8; the drive number, always 0 on the 1541; any desired
name for the diskette, up to
16
characters in length, followed by a 2 character diskette ID
number.
The
Close command is often optional; just
don't
Open that same file again
without Closing it the first time.
EXAMPLE:
OPEN 15,8, 15, "NO:MY FIRST
DISK,01":
CLOSE
15
Note: the chattering
or
thumping noise you hear
just
after the disk New command
begins is entirely normal. The disk must be sure it is at track 1, which it assures by
stepping outward 45 times (on a 35 track diskette.) The noise you hear is the head
assembly hitting the track 1 bumper after its inevitable arrival.
HOW
TO
PREPARE A NEW DISKETTE: BASIC 3.5
A diskette needs a pattern
of
magnetic grooves in order for the drive's read/write
head to find things on it. This pattern
is
not on your diskettes when you buy them, but
adding it to a diskette is simple once you know to do it. Here is the procedure:
FORMAT
FOR
THE
HEADER COMMAND
HEADER
"diskette
name"
,lid,Ddrive
#,Udevice
#
Where
"diskette
name"
is any desired name for the diskette, up to
16
characters in
length;
"id?'
is a 2 character diskette ID number;
"drive
#"
is the drive number, 0
if
omitted (as it must be on the 1541); and
"device#"
is
the
disk's
device number, assumed
to be 8
if
omitted. As described in the next page,
"id"
is optional if
(.and
only if) the
diskette has been previously formatted on a 1541. Also, the ID must be a string literal, not
a variable
or
expression, and may not include Basic reserved words. Thus,
",IFI"
cannot
be used because
If
is a Basic keyword, and
",l(A$)"
is not allowed because A$ is a
variable. "
,IA$"
is
allowed, but the ID number will be the letter
"A"
plus a dollar sign
($),not
the contents
of
the variable A$.
If
you need a variable ID number, use the Basic 2
form
of
the format command.
EXAMPLE:
HEADER
"MY
FIRST DISK,101,DO"
Note: the chattering
or
thumping noise you hear
just
after the Header command
begins is entirely normal. The disk must be sure it is at track 1, which it assures by
stepping outward 45 times (on a 35 track diskette). The noise you hear is the head
assembly hitting the track 1 bumper after its inevitable.arrival.
REUSING
AN
OLD DISKETTE
After you have once formatted a particular diskette, you can re-format it as
tho,µgh
it
were brand new at any time, using the above procedures. However, you can also change
its name and erase its programs more quickly and easily by omitting the ID number
in
16
your format command. By leaving
off
the
ID
number, the fonnat command will finish
in
a
few seconds instead
of
the usual
90
seconds.
ORGANIZING A DISKETTE LIBRARY
Though you may not believe
it
now, you will eventually have dozens, if not hundreds
of
diskettes. You can ease life then by planning now. Assign each diskette a unique
ID
number when you fonnat it. There are diskette cataloging programs you can buy, that
store and alphabetize a list
of
all your file names, but are
of
limited value unless your
diskette
ID
numbers are unique.
At least two valid approaches are used
in
assigning
ID
numbers. One starts at
00
with
the first diskette, and continues upward with each new diskette, through 99, and then
onward from AA through
U.
. Another organizes diskettes within small categories, and
starts ihe
ID
number for each diskette
in
that category with the same first character, going
from
0 to 9 and A to Z with the second character as before. Thus, all
"Tax
" diskettes
could have
ID
numbers that begin with
''T
. ' ' Either approach works well when followed
diligently.
While on this subject, may we suggest you choose names for diskettes on the same
basis, so they too will be unique, and descriptive
of
the files on them.
BACKUPS
When to do a Backup
Although the
1541
is far more reliable than a cassette drive under most circum-
stances, its diskettes are still relatively fragile, and have a useful life
of
only a few years
in
steady use. Therefore, it is important to make regular backups
of
important programs and
files. Make a backup whenever you wouldn't want to redo your current work. Just as you
should save your work every half hour
or
so when writing a new program, so you should
also back up the
dis~ette
you're
using at least daily while you are changing
it
frequently .
In a business, you would make
an
archival bac;kup every time important information was
due to be erased, such as when a new accounting period begins.
How
to do a Backup
We have included programs on the TesVDemo diskette that can be used for similar
purposes. These programs are described further
in
Appendix E.
How
to Rotate Backups
Once you begin to accumulate backups, you'll want to recycle older ones. One good
method
is
to date each backup. Then retain all backups until the current project
is
finished.
When you are sure the last backup
is
correct, make another backup
of
it
to file. and
m~ve
all older backups to a box
of
diskettes that may be reused.
One
other popular approach, suited to projects that never end,
is
to rotate backups
in
a chain, wherein there are son backups, father backups. and grandfather backups. Then.
when another backup
is
needed, the grandfather
di~kette
is
reused, the father becomes the
grandfather, and the son becomes the father.
Whichever approach
is
used,
it
is
recommended that the newly-made backup become
the diskette that is immediately used, and the diskette that
is
known to
be
good should be
filed away as the backup.
That way,
ifthe
backup fails, you'll know
it
immediately, rather
than after all the other backups have failed some dark day.
17