Brian if you have www access you can get the application notes AN-409 and
AN-759 from National Semi. These are related to RS-485.

You can go via http://www.natsemi.com

However Maxim makes devices with 1/8 unit-load input impedance that
guarantees up to 256 transceivers on the bus. ie MAX1483


>     I need to know the all of the serial standards and what distances
> they are capable of transmitting reliably.  I want to use this with a
> 16C84.  I believe RS485 can transmit a great distance, but what
> distance?

Up to 4000 ft.

> Brian

I hope to make a future project about home automation using a shielded
twisted cable runing RS-485 into the electric conduits.

Good luck and Merry Christmas to all PicListers,
Luiz Marques