executive summary: There's a new USB/serial chip, and it's not
compatible with uplcom(4).  But, there are patches for openbsd and
linux to deal with it.


I ordered six of the Sabrent USB/serial adaptors, expecting to get
ones with the following dmesg (from a friend's adaptor which works
fine under 2.0):

uplcom0 at uhub1 port 2
uplcom0: Prolific Technology PL2303 Serial adapter (ATEN/IOGEAR UC232A), rev 1.10/2.02, addr 2
ucom0 at uplcom0

I received some 'Cables To Go' brand adapators thought to be
equivalent.  Of two examined, one had identical dmesg output, and
worked fine.

The other:

uplcom0 at uhub1 port 2
uplcom0: Prolific Technology Inc. USB-Serial Controller, rev 1.10/3.00, addr 2
ucom0 at uplcom0

will receive data but apparently not send it.

This is said by others to be a Prolific 2303-X:

  http://www.prolific.com.tw/eng/Products.asp?ID=21

Several people have reported success with the chip once driver changes
are made:

  http://www.monkey.org/openbsd/archive/misc/0410/msg01202.html

  http://gate.intercaf.ru/~lesha/6100/