Steve, Finally took time to figure out what I was (or was not) doing to start mComm under macOS Catalina. So far it all looks well. SR & TSDOS ROM images as well as my RAM backup of Personal Finance (PF) are intacted. I was able to activate TSDOS from REXMGR when SR (CALL 63012) was all I could do after the reset.
I used files/image from RXC_11_b43 and noticed REXMGR still at v1.0. Wanted to ask if there is a way to verify the reload/update has taken? In any case it looks to be working fine. Ctrl-C opens CPN et al. Thanks again for REX/REXCPM/MVT100. God Bless, GregS <><
