12 Sep
2002
12 Sep
'02
4:55 p.m.
At 08:53 PM 9/12/02 GMT, you wrote:
All the commercial LocalTalk and Phonenet adaptors
contain an isolating
transformer, which is carefully designed to preserve nice clean square
waves from one side of the interface to the other. Note that you can't
just use any old small transformer! There's a web page describing the
innards at
http://ground.ecn.uiowa.edu/apple2/MiscInfo/Hardware/appletalk.phonenet
-snip-
Thanks Pete! Excellent links. By the way, I had found an apple
PDF file documenting most ports, but the serial mini DIN8 connector
shown in page 2 seems to be have the wrong pin numbering; according
to my own measurements, pin 4 is actually closer to pin 3 than
to pin 5; if the pins were numbered in right to left, bottom-up
order the picture would be right:
http://www.apple.com.pl/infotech/varia/Ports/Ports_Pinouts.pdf
(2MB download)
The document that you referenced shows a numbering that is in accord with
my own measurements. A case of an official document being wrong and a
hobbyist-produced document being right.
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Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org