Hi Steve, The patches you received (or should have) with DCELX60 are MPELXL2 and MPELXL3, these are the actual threads patches and deliver the Posix Draft 10 API. The gcc compiler links with OTHDXL.THREADS.SYS and DCEXL.HPDCE .SYS by default (unless that changed). The OTHDXL file contains the Draft 4 API code. The API wrapper code (ie. pthread_create) are found either in /usr/lib/libdce.a ( use -ldce ) or in DCEXL if you want to go with shared libraries. If you want to use Draft 4 threads and the default linking then you'll need to define _PTHREAD_D4 (see /usr/include/pthread.h). And you should also define _MPE_THREADS too. That might help take care of what you are seeing although the unresolved external you report > _t24__default_alloc_template2b0i0$_S_start_free (LDRERR 512) is not part of any library I know of. That's a C++mangled name or it sure looks like one. If you do wish to use Draft 10 API's then the default linking with OTHDXL and DCEXL won't work. You need to use /usr/lib/libpthread.sl instead. I hope this helps! Best Regards, Bill Cadier HP/CSY << just add '.hpixec01' before the '.cup' to get a legal email address >> * To join/leave the list, search archives, change list settings, * * etc., please visit http://raven.utc.edu/archives/hp3000-l.html *