| Function | Address | Description |
|---|---|---|
| SETLFS | FFBA | Setup a logical file |
This routine sets the logical file number, device address, and secondary address (command number) for other KERNAL routines.
The logical file number is used by the system as a key to the file table created by the OPEN file routine. Device addresses can range from 0 to 31. The following codes are used by the Commodore 64 to stand for the CBM devices listed below:
| Address | Device |
|---|---|
| 0 | Keyboard |
| 1 | Cassette / Datassette |
| 2 | RS232 |
| 3 | Screen |
| 4 | Printer |
| 8 | Disk drive |
| 9 | Disk drive |
Device numbers 4 or greater automatically refer to devices on the serial bus.
A command to the device is sent as a secondary address on the serial bus after the device number is sent during the serial attention handshaking sequence. If no secondary address is to be sent, the Y index register should be set to 255.