> What value resistor would be appropriate for a pullup on my 300 baud,
> open collector serial port (no level shifting, just straight 5volt logic
> levels at both ends) with a 6' audio cable. Battery operated so I want a
> minimal value.

Is this simplex on one line or two circuits simplex or two circuits
duplex ? For duplex you need more pullup. For simplex and 6' you can
probably use 100k. You can also set break state on the serial so no power
will be drawn when not in use, or use inverters so idle line is high. I
would use 10k at most pullups. Things happen with connectors and wires. I
discovered that I can make my mouse pointer move (in one direction) if I
use my cell phone within 1' of it. iow ymmv (quite a lot).

Peter

PS: Russell: I have been trying to send you email for a few days now and I
can't. The server says your mailbox is full or such. Can you please
clarify this and contact me offlist ?

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics