Tandy TRS-80 Owner Manual & Programming Manual page 18

MEET YOUR
DISK
just
LOADed
a
program
called
"SIMPLE/PRO"
into
memory,
right?
Change
it
by
typing:
20
PRINT "WITH THIS CHANGE"
(ENTER]
LIST
the
program
again
to
see that the
Computer
has registered the
changed
line
20
in
its
memory:
10
PRINT "STORE
ME
IN A
DISK FILE"
20
PRINT "WITH THIS CHANGE"
Store
it
in a different
file
by typing SAME
"CHANGE"
[ENTER)
...
Hear
the
whirring and grinding from
your
disk
drive?
You have two
disk
files
now:
"SIMPLE/
PRO"
and
"CHANGE"
What
do
you think each
of
them
contains?
Try
LOADing
and
then
LISTing
both
of
them.
[Note:
You
don't
need
to
type
NEW
(EBTER] before
LOAD-
ing
a new program
into
memory. The Computer
will
automatically erase everything
you
presently
have
in
memory
before
LOADing
the
new
program.
??????????????????????????????????????????????????
"CHANGE"
contains the
changed program:
10
PRINT "STORE ME
IN
A
DISK FILE"
20
PRINT "WITH THIS CHANGE"
However,
"SIMPLE/PRO"
still
contains the
old
program:
10
PRINT "STORE ME
IN
A
DISK FILE"
20
PRINT "AND YOU'LL NEUER LOSE ME"
NEW
[INTEH]
10
PRINT "CHANGED FILE"
(ENTER]
SfliJE
"SIMPLE/PRO"
(ENTER)
FILENAMES
You
have
already
used one
filename:
"SIMPLE/PRO"
If
you
did
our
memory
vs.
disk storage
exercise,
you've used
a second filename:
"CHANGE"
We
gave the
name "SIMPLE"
an
"extension"
—
"PRO."
You must
give everything you
store a
name. The
extension
is
up
to
you.
It's
optional.
What names
can you
give
your
files?
Anything
you
want, as long as
you
follow
these
rules:
1.
The name may
have no more
than
eight
characters.
2.
If
you
give
it
an
extension, the extension
may
have no more than
three characters.
3.
There
must
be a slash
(/)
or a
period
(.)
between
the
name
and
the extension.
Fair enough?
Good.
Note: You
may
use
any
characters
in the filename
except
a
colon
(:)
or a zero
(0).
You can
only use
a
slash
(I)
or a period
(.)
to
separate the
name
from
th
extension.
The
only
way
to
change a
disk
file is
by
. . .
well,
you answer
it.
How
can you
make
the
file
"SIM-
PLE/PRO"
contain:
10
PRINT "CHANGED FILE"
??????????????????????????????????????????????????
Answer:
T>pe:
10
FILENAMES
WHEN
YOU HAVE
MORE THAN
ONE
DRIVE
If
you have more than one
disk
drive,
you can add
the drive
number
to
your
filename.
(Remember,
you
numbered
all
of
your
drives in
Chapter
1
),
For
example:
LOAD "SIMPLE/PRO:!"