Transferring data using an IrDA-compatible infrared connection at a rate up to 115 kBaud. As opposed to Fast Infrared which can transfer data at a rate up to 4 MBaud. The MessagePad 2000, MessagePad 2100, and eMate 300 utilize Serial Infrared transceivers.
Also referred to as Slow Infrared and SIR.
Smart Dog Software: Newton IrDA White Paper