http://t3x.org/cpnc/nulcable.html (light|dark)
In order to transfer files to the NC100, you will need a nullmodem cable, i.e. a serial cable, DB9 male on the NC100 side, with the RXD/TXD, RTS/CTS, and DCD/DTR lines crossed):
FG ---------- FG TXD ---------> RXD RXD <--------- TXD RTS ---------> CTS --+ Shunt these, if the NC100 can CTS <--------- RTS --+ receive, but cannot send data SG ---------- SG DSR <--------- DTR DCD <--------- DTR DTR ---------> DCD DTR ---------> DSR
A three-wire connection will not work! Use a proper cable! An FTDI or PL2303 USB<->serial cable should work fine.
If the NC100 cannot send data (which is necessary for the XMODEM protocol to work, even when only uploading to the NC100), try shunting pins 7 and 8 (RTS/CTS) in the connector on the NC100 side.