umcs —
USB multiport serial adapters driver
umcs* at uhub?
ucom* at umcs?
The umcs driver supports a wide variety of hardware
  based on the MosChip 7810, 7820, 7840 chipsets and clones thereof. Devices
  range from single port to eight port (implemented as a USB hub and two
  umcs four port instances behind it).
Examples of hardware known to work with this driver are:
The umcs driver attaches the MosChip multiport chipset
  with individual port drivers via
  ucom(4), which makes it behave
  like a tty(4).
The umcs driver appeared in NetBSD
  7.