mrln55,
Back in the seventies, "NC" meant that there was no internal connnection, and it's probably true
for 90% of the ICs. Unfortunately, some newbies would put "NC" on a data sheet when they
meant for you to put No Connection on that pin. A few years ago, the precision op amp group
starting putting "NIC" on the data sheet to mean "No Internal Connection" and "DNC" to mean
"Do Not Connect". I looked at the bonding diagram for the AD820 in the SOIC package,
and the NC pins have no bond wires on them. If you are using a different package, let me know.
Harry