On Tue, Jan 14, 2020 at 2:29 PM Charles H Sauer <sauer@technologists.com> wrote:

AIX on 386 & 370 probably used a.out. Clem probably knows.

I don't remember for sure, but I think that's right. It might have used COFF, given the time frame but I don't think so since it was originally targetted for University/Research sites which were a.out oriented.