Commodore PET User Manual page 256

To write from a program to a data tape use the PRINT# command:
PRINT#f.data
where:
is the logical file number (1-255. must match the f in the OPEN and CLOSE
commands).
data is the data to be written.
PRINT# cannot be typed as PRINT # or 7#. PRINT# must be completely spelled
out when referencing files.
PRINT# transfers data one character at a time to a cassette buffer
before sending the data to the tape. When the cassette buffer reaches its
maximum capacity of 191 bytes of data, the cassette buffer stops accepting
data, and sends the data in the buffer to the data tape as a "block" of data. A
block may contain a partial record. a single record. or several records of data.
Data
on screen
Data
in memory
Data in
cassette
buffer
Data
on cassette
Either numeric constants or strings may be transferred with the PRINT#
statement. Figure 5-5 shows the flow of the PRINT# process.
Writing Numbers
Writing numbers to a data tape is similar to printing numbers on the screen.
Let's write a program called NUM.PRINT#. to write the numbèrs 1 through 10 on
a data tape. where each number is a single record.
The first action of the program is a display of the program function and load
instructions:
NUMPRINT#
10
PRINT"~.
CREATE NUMERIC DATA TAPE .... :PRINT
20 PR 1
NT....
MOUNT TAPE; PRESS <RETURN> WHEN READY •• ": F'R1NT
3(1
OET A$; 1F A$:::.... THEN
30
Line 20 instructs the user to insert the data tape in the cassette unit and rewind it
to the beginning of the tape. Once the data tape is ready for writing. press
RETURN. Line 30 is a wait loop which waits for RETURN or any key to be pressed.
If no keystroke is entered. it waits.
This wait loop is important because it doesn't let the PET do anything
until vou have loaded a data tape. If line 30 were deleted and there were no wait
loops. the PET would give the user no time to mount and rewind the data tape. As
soon as any cassette button was depressed. the PET would attempt to open the
file. even if vou were trying to rewind the data tape.
Once a key is pressed. A$
i= ....
and the program drops down to the next line
to OPEN the mounted data file:
40 PRINT .... OPENINO DATA FILE .... :OF'EN1,1,2,
Il
NUMBERS"
243