[GreenKeys] ASR33 punch reader control line

[Trammell Hudson]

I'm attempting to connect an ASR33 with a current loop interface to a 
modern computer and am not sure how to connect the punch reader control 
lines.  In Local mode the punch reads fine and prints a copy of the tape 
as you can see in this video: 
http://www.flickr.com/photos/osr/8662034542/in/set-72157633270866016

In Line mode, however, the tape reader does not do anything.  I believe 
the control line need to be pulsed to clock in one byte, but have not 
been able to find documentation on the interface specifications.  There 
are two remaining wires in the cable and the label says they are "+12v 
reader" and "Ctrl-line".  So I assume it is not yet another current 
loop, but sending various voltages on the control line (shorted to 
ground, to my interface's +5, to the +12v, etc) did not seem to have any 
affect.

Thanks!

-- 
Trammell