3
282
270
350 310
255
4
310
250
310
280
260
5
280
280 280
280
270
8
285
290
330
275
258
Clear memory with the NEW command and enter the following program:
10
OPEN
"RAM:SALEDA"
FOR
OUTPUT
AS
1
20
FOR
I = 1
TO
30
30
READ
S : PRINT
#It
S :
NEXT
I
40
DATA
280t275t346t280t250
50
DATA
300t260t320t300t242
60
DATA
29ZtZ70t350t310tZ55
70
DATA
310tZ50t310t290tZ60
80
DATA
280t280t290t280t270
80
DATA
285t280t330t275t258
Execute this program.
The only thing which appears
to
happen is that the BASIC prompt
Ok
displays after a second or two. What took place almost instantly, was that the sales
data contained in the DATA statements was written to a RAM file.
List
the
files
by
pressing
ern
to confirm that file
"SALEDA.DO"
has been created.
Line
18 The OPEN statement defines a RAM file with the filename
"SALEDA.DO"
and assigns it a file number
of
1.
Since the file is written to, it is declared an output
file.
Lines
28 • 38 The FOR/NEXT loop repeats 30 times, corresponding to the 30 data
values. Each time through the loop, the next sales value is read from the DATA
statements and then output to file number
1.
Lines 48 .
~
The DATA statements contain the 30 sales values in chronological
order.
Once the RAM file has been created,
it can be used repeatedly with a variety of
analysis and reporting programs. For example, you could use a statistics program to
read the data file and compute the mean and median.
In
fact, the SALEDA. DO file
will be used
in
the next lesson in just this way.
What you have learned:
Y
ciu
should now be able to read and write data files
to
either RAM or cassette. Recall
that RAM files are more convenient but use valuable memory. On the other hand,
cassette files require an external device, but allow essentially unlimited data storage.
You also learned how the logical operator NOT may be used to simplify the condition
in
an IF statement.
129
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