Need a bus driver solution

That sounds like a suggestion from the olden days with slew rate limited transitions and nice long mucho microsecond settling time waits before receiver latches data off the unterminated lines- well the whole idea was to make the line into a simple wire and circumvent xmission line effects.

well sorry i spoke. All I suggested was what I'd seen on a scope monitoring a few signals in the lab, and empirically tried a few things, more from curiosity than anything else, I was just trying to give someone the benefit of my personal experience - which is mostly not transmission line related. Theory is great, but I've seen too many circuits which were theoretically perfect (according to the calculations done by the designer) that didn't work in practice. As to the aircraft, yes there are many much more competent designers than me working on the flight circuits, and all hardware goes through rigorous enviromental and stress tests before going anywhere near an aircraft, then goes through ground tests, then flight tests ... so I'm quite happy to fly in them. Perhaps one day I'll know enough to write a reply to a question which doesn't attract so much criticism. And please excuse any spelling or grammar mistakes.

I've noticed that some "bus driver" devices (no doubt out of date now) had series resistors on the outputs, and that some of our newer circuits which have small surface mount devices also have such resistors (10R I think). When I asked about them, I was told "to stop ringing and stuff coz the devices are so small there is no parasitic lead inductance any more" so I assumed they were a good idea. Does the ground plane on the pcb make these device outputs act like a 'pair' or transmission line with the ground plane? 'scuse my ignorance, I'm just curious and know not a lot. Neil

IEEE-488 does bytewide data exchange, or look at the LTC design note DN168.... RS485 operating at 52Mps over 100ft of shielded pair... Cat5 cable basically.