diff --git a/README.md b/README.md
index fc8864f0..c98975c5 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,7 @@
         when connected to serial ports).
     DHU11 (device VH) on Unibus systems now has 16 ports per multiplexer.
     MicroVAX 3900 and MicroVAX II have SET CPU AUTOBOOT option
+    MicroVAX 3900 has a SET CPU MODEL=(MicroVAX|VAXServer) command to change between system types
 
 #### Terminal Multiplexer additions
     Added support for TCP connections using IPv4 and/or IPv6.
diff --git a/VAX/vax_sysdev.c b/VAX/vax_sysdev.c
index 86353b26..d8b68bd2 100644
--- a/VAX/vax_sysdev.c
+++ b/VAX/vax_sysdev.c
@@ -1623,17 +1623,12 @@ if (*rom == 0) {                                        /* no boot? */
     r = cpu_load_bootcode (BOOT_CODE_FILENAME, BOOT_CODE_ARRAY, BOOT_CODE_SIZE, TRUE, 0);
     if (r != SCPE_OK)
         return r;
+    rom_wr_B (ROMBASE+4, sys_model ? 1 : 2);            /* Set Magic Byte to determine system type */
     }
 sysd_powerup ();
 return SCPE_OK;
 }
 
-t_stat cpu_print_model (FILE *st)
-{
-fprintf (st, "MicroVAX 3900 (KA655)");
-return SCPE_OK;
-}
-
 t_stat sysd_set_halt (UNIT *uptr, int32 val, char *cptr, void *desc)
 {
 ka_hltenab = val;
@@ -1698,6 +1693,24 @@ char *sysd_description (DEVICE *dptr)
 {
 return "system devices";
 }
+t_stat cpu_set_model (UNIT *uptr, int32 val, char *cptr, void *desc)
+{
+if ((cptr == NULL) || (!*cptr))
+    return SCPE_ARG;
+if (MATCH_CMD(cptr, "VAXSERVER") == 0)
+    sys_model = 0;
+else if (MATCH_CMD(cptr, "MICROVAX") == 0)
+    sys_model = 1;
+else
+    return SCPE_ARG;
+return SCPE_OK;
+}
+
+t_stat cpu_print_model (FILE *st)
+{
+fprintf (st, "%s 3900 (KA655)", (sys_model ? "MicroVAX" : "VAXServer"));
+return SCPE_OK;
+}
 
 t_stat cpu_model_help (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, char *cptr)
 {
diff --git a/VAX/vax_syslist.c b/VAX/vax_syslist.c
index fed69143..df1f9d38 100644
--- a/VAX/vax_syslist.c
+++ b/VAX/vax_syslist.c
@@ -30,7 +30,7 @@
 
 #include "vax_defs.h"
 
-char sim_name[] = "VAX";
+char sim_name[] = "MicroVAX 3900";
 
 extern DEVICE cpu_dev;
 extern DEVICE tlb_dev;
diff --git a/VAX/vaxmod_defs.h b/VAX/vaxmod_defs.h
index 1d03939a..a037e9ae 100644
--- a/VAX/vaxmod_defs.h
+++ b/VAX/vaxmod_defs.h
@@ -126,12 +126,12 @@
                         { UNIT_MSIZE, (1u << 27), NULL, "128M", &cpu_set_size }, \
                         { UNIT_MSIZE, (1u << 28), NULL, "256M", &cpu_set_size }, \
                         { UNIT_MSIZE, (1u << 29), NULL, "512M", &cpu_set_size }
-#define CPU_MODEL_MODIFIERS                                                         \
-                        { MTAB_XTD|MTAB_VDV, 0,          "MODEL",      NULL,        \
-                          NULL, &cpu_show_model },                                  \
-                        { MTAB_XTD|MTAB_VDV, 0,          "AUTOBOOT",   "AUTOBOOT",  \
-                          &sysd_set_halt, &sysd_show_halt },                        \
-                        { MTAB_XTD|MTAB_VDV|MTAB_NMO, 1, "NOAUTOBOOT", "NOAUTOBOOT",\
+#define CPU_MODEL_MODIFIERS                                                             \
+                        { MTAB_XTD|MTAB_VDV, 0, "MODEL", "MODEL={VAXServer|MicroVAX}",  \
+                          &cpu_set_model, &cpu_show_model },                            \
+                        { MTAB_XTD|MTAB_VDV, 0,          "AUTOBOOT",   "AUTOBOOT",      \
+                          &sysd_set_halt, &sysd_show_halt },                            \
+                        { MTAB_XTD|MTAB_VDV|MTAB_NMO, 1, "NOAUTOBOOT", "NOAUTOBOOT",    \
                           &sysd_set_halt, &sysd_show_halt },
 
 
diff --git a/doc/simh_faq.doc b/doc/simh_faq.doc
index 244ecfd5..fc2ddb13 100644
Binary files a/doc/simh_faq.doc and b/doc/simh_faq.doc differ