Experience shows that at *all* data/address buses, it is strongly
recommended to pull up at the end of the bus, and then it comes
to be named as "termination resistors".

The main idea is avoid "open ends" on the tracks and wires, so
the terminators eliminate reflected waves and turns pulses a little
bitter better on scope, reducing also EMI.

Open collectors circuits require pull up terminators, but some
I/O microchips supply pull up for its own interest, not to the
interest of the microprocessor. Sooooo, what doesn't hurt...

"Long Life to the Terminated Circuits..."

--------------------------------------------
Wagner Lipnharski - Orlando, FLorida
microcontroller website: http://www.ustr.net