### Requirements and Considerations

Use this topic for planning purposes.

#### Requirements

- The RealPort driver for Microsoft Windows NT requires between one and two MB of memory on the Windows NT system.
- The Windows NT RealPort driver requires a 10-pin RJ-45 cable to connect devices to Digi One RealPort or PortServer ports.

#### Limitations

- Version 1.0.2 of the RealPort driver is the only version that supports Windows NT systems. You can access this driver at the Digi Web site: http://www.digi.com.
- Only TAPI-compliant applications or those written to COM 32 API (application programming interface) standards can use intelligent ports, which means only these applications can use RealPort ports.

#### Key Concept: About Port Mapping Offsets

The number of local ports on the Windows NT host offsets the port number on the Digi device. For example, if you have two local COM ports, Port 1 of the Digi device is seen by the RealPort service as COM 3.