Radio Shack TRS-80 - Page 225

One last
word of
advice:
If
you
PRINT
# a list of, say,
10
values
onto tape,
you
should
INPUT # a
list of
10
values also.
If you don't match up
the number
of PRINT
# items
with the number of INPUT
#
items, you'll end up
either losing
data
or going into the
lock-up condition described above.
The
following
program demonstrates how a data file can
be used to create
a
list
of data
items, process and update it.
Study it carefully
and think how similar
programs might
handle inventories, or
any sequential
lists.
1 REM
5 C
=
7 B
=
10 IN .
*AVG
CLS
TEMP AND
HUMIDITY
USING
A
DATA
FILE*
20
30
40
50
53
55
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
2 10
220
230
240
250
"WHAT DAY
OF
'WHAT
WAS THE
THE MONTH
IS IT" ;D
TEMPERATURE
TODAY "
;T
,
"
WHAT WAS THE
D=l
THEN
160
HUMIDITY "
;H
IN
IN
IF
P.
"LOAD
PREVIOUS
TEMPERATURES AND
P. "FIRST REWIND TAPE TO BEGINNING
P,
"THEN
PRESS
RECORDER'S
PLAY
KEY
IN. "PRESS
ENTER WHEN READY" ;A$
FOR X=l TO D-
1
INPUT #
Y.Z
B
=
B+Y
C
=
C+Z
NEXT X
B=( B
+
T )/D
C=CC+H)/D
CLS:P. "THE
AVERAGE
HUMIDITIES
THIS MONTH."
OF
DATA
FILE.
"
TEMPERATURE
IS"
;B
"THE AVERAGE HUMIDITY IS";C
sP.
"NOW THE TRS-80
WILL
WRITE"
"TODAY'S
TEMPERATURE
AND
HUMIDITY"
"ONTO THE
TAPE.
"
"SO
PRESS
RECORD
AND
PLAY KEYS"
"BUT
DO NOT REWIND."
IN. "PRESS ENTER
WHEN READY"
;A$
PRINT
n T;
"
,
"
;H
P.
tP. "NOW
TODAY'S
INFO IS
ADDED TO THE
TAPE
P
.: P. "PLEASE
PRESS STDP KEY
ON THE RECORDER
END
P.
P ,
P.
P,
P.
P,
FILE
ii
Line
70
reads
back
all the
previous days'
numbers,
two at a time.
When all
the information
is
read in, the average
temperature
and
humidity
are
calculated
(using
the current day's
info
as well).
Line
2
1
then writes the
current
day's information
at the end
of
the list.
223