| Switch 1 | Switch 2 | Meaning |
| Up | Up | 8 pin AppleTalk (Serial Port Disabled) |
| Down | Up | 25 pin RS-232 and 8 pin RS-422 *
Serial Ports 1200 baud |
| Up | Down | 25 pin RS-232 and 8 pin RS-422 *
Serial Ports 9600 baud |
| Down | Down | 25 pin RS-232 serial port 9600 baud;**
8 pin RS-422 serial port 0 baud |
| Switch 3 | Switch 4 | Meaning |
| Up | Up | PostScript Batch |
| Down | Up | Diablo 630 |
| Down | Down | HP LaserJet |
| Up | Down | PostScript Interactive |
| Switch 5 | Switch 6 | Meaning |
| Down | Down | No Handshake |
| Up | Up | ON/XOFF |
| Down | Up | Etx/Ack |
| Up | Down | DSR |
* Both serial ports are enabled. Serial communication and AppleTalk communication are NOT compatible, and will never occur at the same time.
** This configuration allows you to use the 25 pin RS-232 port while leaving LocalTalk connected. This prevents serial communication from interfering with the AppleTalk Network.
The switch configuration settings are maintained between power-off and power-on cycles by the 2K battery-backed-up ZPRAM (Zero-Power-RAM) equivalent to the EEROM of the LaserWriter IINT. The same PostScript commands that are used to modify the EEROM parameters will ALSO set or read the ZPRAM parameters. Consistency between the switch configurations and the ZPRAM is maintained through the VIA. Toggling a switch, waiting 30 seconds, then toggling the switch back forces the ZPRAM to update to the current switch settings.