Here is the full source code to System-X BBS software.
It's written to compile on SAS/C.

If anyone wished to continue development on this software,
please contact me via email (zed@mentasm.com).

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                  254     628  40.4% -lh5- 3d73 Aug 13  1998 sxsrc.info
[generic]                10430   10430 100.0% -lh0- ea10 Oct  8  1998 sxsrc/Include.lha
[generic]                  577    1057  54.6% -lh5- 29ad Aug 13  1998 sxsrc/README.TXT
[generic]               107888  107888 100.0% -lh0- 5f3b Aug 13  1998 sxsrc/SX.lha
[generic]                63635   63635 100.0% -lh0- 5e29 Aug 13  1998 sxsrc/SXConfig.lha
[generic]                21622   21622 100.0% -lh0- ad97 Aug 13  1998 sxsrc/SXMCP.lha
[generic]                15253   15253 100.0% -lh0- cc64 Aug 13  1998 sxsrc/UserED.lha
[generic]                20426   20426 100.0% -lh0- 1c0f Aug 13  1998 sxsrc/Utils.lha
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         8 files  240085  240939  99.6%            Nov  3  1998