N.C. pins, Not Connect pins

However, this "explanation" (for a S-III) makes it more complicated than it needs to be:

http://www.altera.com/literature/dp/stx3/pcg-01004.pdf

This document lists N.C. as:

--- Quote Start ---

Do not drive signals into these pins.

When designing for device migration these pins may be connected to power, ground, or a signal trace depending on the pin assignment of the devices selected for migration. However, if device migration is not a concern leave these pins floating.

--- Quote End ---

That's not much help...

N.C. is a very abused term these days. It use to mean "No Connection", meaning that there was no internal connection to the electronics of the chip. These pins could be used for heat conduction, to make routing other pins easier, preparing for future chip upgrades, or just on a whim.

Recently I have seen pins marked "N.C." on the data-sheet internally connected to a disable on a switching power-supply, and vcc on a flash memory. In both of these cases, grounding the "N.C." pins caused rather severe problems.

Another data sheet listed N.C. as

--- Quote Start ---

No Connection. These pins must be connected to ground.

--- Quote End ---

... What!?

I thought Altera was being helpful when they listed two types of pins on the S-III, N.C. and DNU (Do Not Use). After reading the document above, I went back to my schematic/artwork and floated all the N.C. pins.

Not a lot of help here, I know. But this is me renewing my call to those in charge of such things... [tirade] Don't just scatter N.C. around if you're getting bored. If it is not a N.C. pin, call it something else! There are lots of good names available, like Vcc, Gnd, disable, DNU, etc. Use the name that matches the pin's purpose! Leave N.C. for those pins that have *No Connection* inside the chip![/tirade]