[maryh@transi /usr/tmp]$ ps2pdf A_file.tang.2319spec.ps
Unknown device: pdfwrite

The wrong version of gs is being used. The version of gs that comes with the Mentor Graphics software is old. We should use version 5.1, which is located at /opt/gs. If you run, which gs, the version that should come up is /opt/gs/bin/gs. If the version that comes up is /net/mgc/mgc_C.2/bin/gs, remove or rename that link. I usually just rename it to /net/mgc/mgc_C.2/bin/gs.old. Be warned though that the link gets automatically remade whenever the Mentor install program is run and the software tree gets rebuilt.