Being frustrated with various device pinouts, I've 'published' a diagram (it's an Excel Book) of various Serial port pinouts here:
http://tchrapkiewicz.googlepages.com/hp48
[Serial Ports Link]
I can add the HP49 pinout once I find one.
Also, the pic at the top of the page is an overlay (still working on getting the layers lined up) of both sides of an HP48 PCB.
TomCee