It may be that Metaware was available for AIX on the RT, but, if so, not bundled with AIX. AIX 1 releases bundled a fairly vanilla pcc as provided by ISC. AIX 2 releases bundled pcc with the HCR optimization phase added. I’m not sure about AIX 3 and beyond, since I left before they were released. The “strategic” plan was a reimplementation of the PL.8 compiler as a C compiler with the work done by an IBM group in Toronto. I suspect that was extra cost option and that pcc with HCR was still bundled in the base. I have the impression that AOS (BSD for RT) eventually also included the HCR phase. See https://notes.technologists.com/notes/2017/03/08/lets-start-at-the-very-beginning-801-romp-rtpc-aix-versions/ for more context. CHS