Commodore Plus 4 - Page 367

The Disk Drive 388
Close
Files can be closed individually with the CLOSE ($FFC3) routine:
1. Load .A with the logical file number of the file to be closed. Call CLOSE
($FFC3).
2. Check for errors by examining the carry bit, status byte, and disk error
channel. Generally, checking the carry bit and disk error channel is sufficient.
All the files in use can be closed and the input and output channels reset to their
default devices by calling CLALL ($FFE7).
Print
To send information into a file, it must have been opened with a mode of write.
The following outlines the operations required:
1. Load .X with the logical file number of the output file. Designate it as the
output channel by calling CHOUT ($FFC9).
2. Check for errors.
3. Send the data to the channel with BSOUT ($FFD2).
4. When all data has been sent, return the input and output channels to default
(keyboard and screen) by calling CLRCH ($FFCC) and close the file. Or call
CLALL ($FFE7) to close all files and reset the input and output channels.
Get
To receive information from a file, it must have been opened with a mode of
read (no mode defaults to read). The following outlines the operations required:
1. Load .X with the logical file number of the input file. Designate it as the input
channel by calling CHKIN ($FFC6).
2. Check for errors.
3. Receive the data from the channel with BASIN ($FFCF).
4. When all data has been received, return the input and output channels to
default (keyboard and screen) by calling CLRCH ($FFCC) and close the file.
Or call CLALL ($FFE7) to close all files and reset the input and output
channels.
Example: This example opens a new file called D ATFIL and writes data accepted from the
keyboard to it. It then closes the file, reopens it for reading, and retrieves the data,