Now that FieldWorks 9.0 has been released as stable, it has replaced FieldWorks 8.3 in the
packages.sil.org software repository. But it's still possible to manually download and install FieldWorks 8.3 for Wasta/Ubuntu 18.04 (bionic) and 16.04 (xenial).
(Note: FieldWorks 8.3 is not available for Wasta/Ubuntu 20.04 (focal). But FieldWorks 9.0 is.)
This is a somewhat more advanced activity than normal software installation.
You can follow the instructions in the README.txt file at
I only did some limited testing of this, on Ubuntu 18.04 (bionic). But it appears to work fine, and `sudo apt upgrade` doesn't upgrade from FW 8.3 to FW 9.0 afterward.
This is not the normal way that we publish software, so there may be some additional bumps along the way.
Mark