News from Mac OSX - Mysterious Serial Port

[Dar Scott]

On Thursday, August 21, 2003, at 09:09 PM, Sarah wrote:

> I'd like to try making one of these loop-back circuits. I'm pretty 
> neat with a soldering iron, but I'm not sure how to proceed. I guess I 
> just need the join the Tx pins to the Rx pins but which pins are they? 
> How did you do it?

I don't know why I asked which one.

On DB9 and DB25, if you don't need handshaking, just connect pin 2 to 
pin 3.  If you need handshaking on DB9, connect 7 to 8, and pin 4 to 6 
and 1.  If you need handshaking on DB25, uh, I forgot--I can look it up.

On the Mac DIN, you get an old mac serial cable and cut it.  Strip the 
wires.  Find those that go to certain pins and then solder or connect 
together like this:

Pin 3 to 5
Pin 6 to 8

This takes two because the signal is on two wires and not one.

If you need handshaking, try 1 to 2.  I have not done that.

If you blow something up, uh, somehow it is not my fault.  There are 
lots of web pages that have info on this; double check with those.

Dar Scott