I was able to compile Maximus BBS on CentOS 6.5, x86_64 with gcc 4.4.7 20120313 (Red Hat 4.4.7-4). There were a few minor changes required to successfully build Maximus with recent (gcc-4.x) compilers, e.g. include statements for <new.h> had to be changed to <new> etc.
After compiling and installing Maximus, I went on to compile all the scripts in the <maximus>/m directory, using MEX. These scripts compile without problems but: once these scripts are run from within Maximus, they throw the following error:
! 05 Jun 09:07:17 MAX MEX: fatal cs:ffffffffffffffff: kill_str: non-global seg
Since I do not have engough knowledge in building compilers with flex / yacc, I can only assume that this issue is related to changes in gcc 4.x compiler directives or optimizations.
The code itself seems to be OK, as Maximus BBS still compiles on an old Debian 3.1 System running gcc-3.3 - there, the error mentioned above does not occur.
Please, please, pleeeease - if anyone more competent than I am could have a look at this issue and (maybe, hopefully) fix it, I'd be very grateful!
There are only a few open-source BBS servers left out there and I really think that Maximus still is a useful program and I'd really like to run it on a modern Linux OS.