clockport —
introduction to clockport bus support and drivers
clockport* at a1k2cp0
clockport* at gencp?
Clockport is a general purpose non-autoconfiguring expansion bus, originally
  present on the Amiga 1200, as a part of P9 memory connector.
The NetBSD includes the following clockport drivers:
  - com(4)
- Individual Computers SilverSurfer 16C550-based serial port.
 
The clockport interface and drivers for it are
  implemented within the sys/arch/amiga/clockport
  directory.
The clockport subsystem appeared in
  NetBSD 7.0.
Clockport performance is very low, even by Amiga standards.
Probing the hardware on clockport might be unreliable.