I have four object files created by C51 compiler, one of them RTXCONF.obj. I'm not using banking. I used the commnad: 1)L51 f1.obj,f2.bj,f3.ob,f4.obj To f.abs 2)L51 f1.obj,f2.obj,f3.obj,f4.obj,RTX51 To f.abs in both cases I got the same error: Fatal error 234:use RTX-51 SWITCH. Anyone knows what missing Thanks