I have Oracle 8.0.5 installed on NT and tried to intall oracle 8.1.6 on same machine but different directory.
I used Oracle Universal Installer and almost at the end in the configuration tool window there were errors which is following below.
For net8 configuration assistant-
Parsing command line arguments:
Parameter "orahnam" = ora8i
Parameter "instype" = typical
Parameter "inscomp" = client,net8,javavm,server,ano
Parameter "insprtcl" = nmp,tcp
Parameter "cfg" = local
Parameter "authadp" = NO_VALUE
Parameter "nodeinfo" = NO_VALUE
Parameter "responsefile" = NO_VALUE
Done parsing command line arguments.
IOException: Can not create NetProperties: C:\orant\network\tools\NetProperties
java.lang.NullPointerException
at oracle.net.ca.CmdlineArgs.saveParameters(Compiled Code)
at oracle.net.ca.NetCA.<init>(NetCA.java)
at oracle.net.ca.NetCA.main(NetCA.java)


For Oracl Data migration assistance error-
java.lang.UnsatisfiedLinkError: no null\bin\JNLSLib3 in shared library path
at java.lang.Runtime.loadLibrary(Compiled Code)
at java.lang.System.loadLibrary(System.java:561)
at oracle.ntpg.jnls.JNLSLib.<init>(JNLSLib.java:473)
at oracle.ntpg.jnls.JNLSLib3.<init>(JNLSLib3.java:52)
at oracle.ntpg.jnls.JNLS.<init>(JNLS.java:292)
at UpgradeConfigInfoBase._dbJNLS(UpgradeConfigInfoBase.java:727)
at UpgradeConfigInfoBase.SetInitParameters(UpgradeConfigInfoBase.java:1091)
at dbmig.main(Compiled Code)