diff --git a/PDP11/pdp11_sys.c b/PDP11/pdp11_sys.c
index 5973627e..4ff2ef1a 100644
--- a/PDP11/pdp11_sys.c
+++ b/PDP11/pdp11_sys.c
@@ -243,8 +243,10 @@ t_stat sim_load (FILE *fileref, char *cptr, char *fnam, int flag)
 int32 c[6], d, i, cnt, csum;
 uint32 org;
 
-if ((*cptr != 0) || (flag != 0))
+if (*cptr != 0)
     return SCPE_ARG;
+if (flag != 0)
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 do {                                                    /* block loop */
     csum = 0;                                           /* init checksum */
     for (i = 0; i < 6; ) {                              /* 6 char header */
diff --git a/VAX/vax610_syslist.c b/VAX/vax610_syslist.c
index adf7fc2a..35c808f6 100644
--- a/VAX/vax610_syslist.c
+++ b/VAX/vax610_syslist.c
@@ -109,7 +109,7 @@ int32 i;
 uint32 origin, limit;
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 origin = 0;                                             /* memory */
 limit = (uint32) cpu_unit.capac;
 if (sim_switches & SWMASK ('O')) {                      /* origin? */
diff --git a/VAX/vax630_syslist.c b/VAX/vax630_syslist.c
index 808d72d4..c8adb379 100644
--- a/VAX/vax630_syslist.c
+++ b/VAX/vax630_syslist.c
@@ -125,7 +125,7 @@ int32 i;
 uint32 origin, limit, step = 1;
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 if (sim_switches & SWMASK ('R')) {                      /* ROM? */
     origin = ROMBASE;
     limit = ROMBASE + ROMSIZE;
diff --git a/VAX/vax730_syslist.c b/VAX/vax730_syslist.c
index 30184665..54c4b1f0 100644
--- a/VAX/vax730_syslist.c
+++ b/VAX/vax730_syslist.c
@@ -108,7 +108,7 @@ int32 val;
 uint32 origin, limit;
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 origin = 0;                                             /* memory */
 limit = (uint32) cpu_unit.capac;
 if (sim_switches & SWMASK ('O')) {                      /* origin? */
diff --git a/VAX/vax750_syslist.c b/VAX/vax750_syslist.c
index b3abd741..ae6384ad 100644
--- a/VAX/vax750_syslist.c
+++ b/VAX/vax750_syslist.c
@@ -112,7 +112,7 @@ int32 val;
 uint32 origin, limit;
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 origin = 0;                                             /* memory */
 limit = (uint32) cpu_unit.capac;
 if (sim_switches & SWMASK ('R')) {                      /* ROM? */
diff --git a/VAX/vax780_syslist.c b/VAX/vax780_syslist.c
index 511008ac..d71f41c4 100644
--- a/VAX/vax780_syslist.c
+++ b/VAX/vax780_syslist.c
@@ -122,7 +122,7 @@ int32 val;
 uint32 origin, limit;
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 origin = 0;                                             /* memory */
 limit = (uint32) cpu_unit.capac;
 if (sim_switches & SWMASK ('O')) {                      /* origin? */
diff --git a/VAX/vax860_syslist.c b/VAX/vax860_syslist.c
index 659a71ad..a311e6fd 100644
--- a/VAX/vax860_syslist.c
+++ b/VAX/vax860_syslist.c
@@ -118,7 +118,7 @@ int32 val;
 uint32 origin, limit;
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 origin = 0;                                             /* memory */
 limit = (uint32) cpu_unit.capac;
 if (sim_switches & SWMASK ('O')) {                      /* origin? */
diff --git a/VAX/vax_syslist.c b/VAX/vax_syslist.c
index eb684d22..52e15094 100644
--- a/VAX/vax_syslist.c
+++ b/VAX/vax_syslist.c
@@ -120,7 +120,7 @@ extern int32 ssc_cnf;
 #define SSCCNF_BLO      0x80000000
 
 if (flag)                                               /* dump? */
-    return SCPE_ARG;
+    return sim_messagef (SCPE_NOFNC, "Command Not Implemented\n");
 if (sim_switches & SWMASK ('R')) {                      /* ROM? */
     origin = ROMBASE;
     limit = ROMBASE + ROMSIZE;