What is latest Engine to still support SQL Tool Char Based (Dumb Terminals)

I have a customer running Informix SE 5.x that I need to upgrade to the latest engine that still supports the SQL tool (ACE, PERFORM) with character interface for dumb terminals and at the same time will support a Win95 front end developed with Powerbuilder, VB, Access or Delphi? We have a mix of Dumb terminals and PC workstations connected to an Intel / SCO Open Server 5 using serial for terminals and SCO Advanced File/Print for the Win95 to SCO Unix networking. Any suggestions on Win95 Front End Development tools and ODBC drivers are welcomed too.... Thanks in advance....Dale