Commodore PET User Manual page 280

Because GET# reads one character at a time and not a 191-byte block at a
time like INPUT#. it is able to read ail file delimiters and anything else on the
tape. This feature is especially helpful when vou want to read everything that is
written on a bad data tape to find the problem. GET# also allows a single
character to be compared to a status or character value within programs. This will
be demonstrated in the sam pie programs.
The two sample programs in this section will demonstrate how to print out
an entire file including ail file delimiters. and how to print out the MAIL data file
separated into records.
Sample Program 1
The following program. MAIL.GET#1. reads data file MAIL one character at
a time and prints the contents of MAIL on the screen:
MAIL.GET#l
10
PRIHT":'l!'~~~~~~~~~~""""""""""~~""~"""
20 PRmT"" ot"
30 PRIHT"" READ MAIL FILE
w.····
GET#
~"
40 PRIHT"ot ot"
50
PRIHT"ot~""""~"~""""""~"~""""""~"~"":
PRINT: PRUn
60 PR 1
HT"....
PRESS <RETURtD' WHEH TAPE 1S LOADED ..
~"
70 GET A$: IF A$="" THEH 7121
80 PRIHT".~ OPEmHG MAIL FILE ~~": PRIHT: OPEHL 1..0, "MAIL"
90 PRIHT"." MAIL FILE
ot~"
100 IF ST=64 THEN 9999
110 GET#l, X$
1213 1F X$=CHR$ ( 13) THEt·~ X$="
*"
130 PRmT X$;
14121 GOTO 100
9999 PRINT"~~ EHIJ OF MAIL FILE--PROGRAM TERMU~ATED~~"
:CLOSE1:EHD
Lines 10 through 90 are similar to the first lines of MAIL. INPUT=IF (page
262). These lines introduce the program. give instructions for mounting the data
tape. and then open the data file.
Lines 100 through 140 control the reading of the MAIL data file and the
printout of its contents on the screen.
Line 100 checks for an End of File (EOF) status. If an EOF is not encountered.
the data is read at line 110.
1
n line 110. # 1. is the file number and X$ is the varia-
ble name assigned to the data strings. This statement will read the first character
encountered and transfer it through the input buffer to memory.
Then the program drops through to line 120. Line 120 compares the current
value of X$ to a carriage return (CHR$(13)). If the value of X$ is CHR$(13), then the
value of X$ is changed to a FULL GRID • . This change avoids printing a car-
riage return. which would push the cursor to the next line: with the FULL GRID
being printed. the whole file appears as one continuous line. representing how it
is written on the data tape. An example of this will be shown in the sample run.
267