This is a very simple 1200 baud AFSK modem. The modem consists only of a modulator/demodulator chip, usually a TI TCM3105. The computer is responsible for regenerating the receiver bit clock. The modem connects to a serial port, hence the name. Since the serial port is not used as an async serial port, the kernel driver for serial ports cannot be used, and this driver only supports standard serial hardware (8250, 16450, 16550).

This is a modem for 9600 baud FSK compatible to the G3RUH standard. The modem does all the filtering and regenerates the receiver clock. Data is transferred from and to the PC via a shift register. The shift register is filled with 16 bits and an interrupt is signalled. The PC then empties the shift register in a burst. This modem connects to the parallel port, hence the name.

This is a redesign of the par96 modem by Henning Rech, DF9IC. The modem is protocol compatible to par96, but uses only three low power ICs and can therefore be fed from the parallel port and does not require an additional power supply.