Pull the card cage out of the 1400 and check out the T-Rex ASIC sittin' there right on the bottom. All we need to do is noodle out which of the PBX Bridged '030 Slot Signals lead to which of the card cage's header interface pins!

Coincidentally, the card cage mounts all the IR-Talk hardware as well! }

< wonders if T-Rex would work on a IIsi's UN-Bridged '030 slot! 8-o >