Convert or open Oracle 7.3.x database in Oracle 11 I have a very old Oracle 7.x database that I need to open or convert to a new Oracle 11g.
Here's the content of the old database:

control01.ctl
control02.ctl
control03.ctl
findata01.ora
finind01.ora
gstdata01.ora
rbs01.dbf
system01.dbf
system02.dbf
system03.dbf
temp01.dbf
temp02.dbf
tools01.dbf
users.dbf

Note: the .ora files are binary (spfile).
When mounting the old database the following error appears:
ORA-00205: error in identifying control file

Ok, first I've tried to create a pfile from spfile:

create pfile='c:\ora\pfile.ora' from spfile='c:\ora...\findata01.ora'

I get "File created" but the pfile is empty.

I've tried to change the control files to:

alter system set control_files='c:\ora...\control01.ctl,c:\ora...\control02.ctl,c:\ora...\control03.ctl' scope=spfile;

But then I get the error message:

ORA-32001: write to SPFILE requested but no SPFILE is in use

Anyone know what else to try? I'm running out of ideas.

Maybe the database format has changed and it's not possible to open a 7.x database from inside 11.x? Or maybe there's a third-party tool to convert the database format?

Thanks in advance!
You should open your 7.3 database with Oracle server version 7.3. Than you need to export data using legacy exp command and import generated file into Oracle 11g using imp. 
That would be safest path. 

If I remember correctly you can not migrate database directly from 7.3 to 11g version.   

EDIT: 
As mentioned in comment, there are more ways to to get to 11g version. Here is upgrade guide http://docs.oracle.com/cd/E11882_01/server.112/e23633/toc.htm