Tandy TRS-80 - 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:!"