Computer 1 DB9 Computer 2 DB9
--------------- ---------------
5*--------------------------------------* GROUND
*9 *9
*---------------------\ /-----------* DTR
* \ / *
TMT DATA *--------------\ /-->> \/ <<---------* TMT DATA
* x /\ *
RCV DATA *--------------/ \-->> / \ <<---------* RCV DATA
*-----------------/ \---------------* DSR
1* 1*
Pins 2,3 crossed between machines (RCV-TMT)
Pins 4,6 crossed between machines (DTR-DSR)
Pin 5 runs straight through (GROUND)