diff -ru orig.Makefile ./Makefile
--- orig.Makefile	Wed Feb 18 10:50:46 1998
+++ ./Makefile	Wed Feb 18 10:56:07 1998
@@ -16,6 +16,7 @@
 # -DINLINE_FUNCTIONS if your compiler support inline functions (most do)
 # -DDEBUG            prints lots of debugging messages.
 # -DDEBUGGER         compiles in the debugger
+# -DPANIC            halt emulator when you hit an unimplemented interrupt
 # -DKBUK             if you have a UK style 102 key keyboard
 # -DBIG_ENDIAN       if your computer is big-endian (Sparc, 68000 etc)
 # -DCPU_LITTLE_ENDIAN    if your computer is little-endian (80x86 etc)
diff -ru orig.bios.c ./bios.c
--- orig.bios.c	Fri Jun 24 13:39:47 1994
+++ ./bios.c	Wed Feb 18 10:56:07 1998
@@ -657,7 +657,7 @@
         break;
     default:
         printf("unimplement INT 15h function %02X\n",*bregs[AH]);
-#ifdef DEBUG
+#ifdef PANIC
         loc();
         exit_emu();
 #else
@@ -790,7 +790,7 @@
         break;
     default:
         printf("unimplemented INT 1Ah function %02X\n", *bregs[AH]);
-#ifdef DEBUG
+#ifdef PANIC
         loc();
         exit_emu();
 #endif
@@ -991,7 +991,7 @@
         break;
     default:
         printf("Unimplemented INT 13h function %02X\n",*bregs[AH]);
-#ifdef DEBUG
+#ifdef PANIC
         loc();
         exit_emu();
 #endif
diff -ru orig.vga.c ./vga.c
--- orig.vga.c	Wed Jun 22 16:24:51 1994
+++ ./vga.c	Wed Feb 18 10:56:07 1998
@@ -560,7 +560,7 @@
             break;
         default:
             printf("Unimplemented int 0x10 function 0x11 sub-function %02X\n",*bregs[AL]);
-#ifdef DEBUG
+#if PANIC
             loc();
             exit_emu();
 #endif
@@ -584,7 +584,7 @@
             break;
         default:
             printf("Unimplemented int 10 function 0x12 sub-function 0x%02X\n",*bregs[BL]);
-#ifdef DEBUG
+#ifdef PANIC
             loc();
             exit_emu();
 #endif
@@ -615,7 +615,7 @@
     default:
         printf("Unimplemented int 10 function: %02X. AL = %02X  BL = %02X\n",
                *bregs[AH], *bregs[AL], *bregs[BL]);
-#ifdef DEBUG
+#ifdef PANIC
         loc();
         exit_emu();
 #endif