Don't install signals with dedicated registers

devpnc.h

@@ -991,10 +991,15 @@ int devpnc (int class, int func, int device) {
     }
     TRACE(T_RIO, "PNC configured\n");
     devpoll[device] = PNCPOLL*gvp->instpermsec;
+
+    /* can't use signals with NOREGS, so PNC I/O is very slow */
+
+#ifdef NOREGS
     if (signal(SIGIO, pnchavedata) == SIG_ERR) {
       perror("installing SIGIO handler");
       fatal(NULL);
     }
+#endif
     if (gettimeofday(&tv0, NULL) != 0)
       fatal("pnc gettimeofday 1 failed");
     tv0ts = tv0.tv_sec + tv0.tv_usec/1000000.0;

em.c

@@ -6747,8 +6747,9 @@ d_bdx:  /* 0140734 */
       if (delayusec > 1000) {
 	if (gettimeofday(&tv0, NULL) != 0)
 	  fatal("em: gettimeofday 0 failed");
-
-	/* NOTE: on OSX, a signal (sigio for pnc) will interrupt usleep */
+	
+	/* for some reason, the SIGTERM signal handler gets reset
+	   during emulator initialization; this re-installs it */
 
 	{
 	  static int firsttime=1;
@@ -6757,6 +6758,9 @@ d_bdx:  /* 0140734 */
 	    firsttime = 0;
 	  }
 	}
+
+	/* NOTE: on OSX, a signal (sigio for pnc) will interrupt usleep */
+
 	usleep(delayusec);
 	if (gettimeofday(&tv1, NULL) != 0)
 	  fatal("em: gettimeofday 1 failed");