diff --git a/PDP11/pdp11_defs.h b/PDP11/pdp11_defs.h
index 79d5214e..4fed32f3 100644
--- a/PDP11/pdp11_defs.h
+++ b/PDP11/pdp11_defs.h
@@ -518,7 +518,6 @@ typedef struct pdp_dib DIB;
    Massbus devices (RP, TU) do not appear in the Unibus IO page */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 /* Processor registers which have I/O page addresses
  */
diff --git a/PDP11/pdp11_dmc.c b/PDP11/pdp11_dmc.c
index 01469699..ee6d0156 100644
--- a/PDP11/pdp11_dmc.c
+++ b/PDP11/pdp11_dmc.c
@@ -353,14 +353,14 @@ MTAB dmc_mod[] = {
 };
 
 #define IOLN_DMC        010
-DIB dmc0_dib = { IOBA_FLOAT, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_FLOAT, {&dmc_rxint, &dmc_txint} };
-DIB dmc1_dib = { IOBA_FLOAT, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_FLOAT, {&dmc_rxint, &dmc_txint} };
-DIB dmc2_dib = { IOBA_FLOAT, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_FLOAT, {&dmc_rxint, &dmc_txint} };
-DIB dmc3_dib = { IOBA_FLOAT, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_FLOAT, {&dmc_rxint, &dmc_txint} };
+DIB dmc0_dib = { IOBA_AUTO, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_AUTO, {&dmc_rxint, &dmc_txint} };
+DIB dmc1_dib = { IOBA_AUTO, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_AUTO, {&dmc_rxint, &dmc_txint} };
+DIB dmc2_dib = { IOBA_AUTO, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_AUTO, {&dmc_rxint, &dmc_txint} };
+DIB dmc3_dib = { IOBA_AUTO, IOLN_DMC, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_AUTO, {&dmc_rxint, &dmc_txint} };
 
 #define IOLN_DMP        010
 
-DIB dmp_dib = { IOBA_FLOAT, IOLN_DMP, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_FLOAT, {&dmc_rxint, &dmc_txint }};
+DIB dmp_dib = { IOBA_AUTO, IOLN_DMP, &dmc_rd, &dmc_wr, 2, IVCL (DMCRX), VEC_AUTO, {&dmc_rxint, &dmc_txint }};
 
 DEVICE dmc_dev[] =
 {
diff --git a/PDP11/pdp11_rq.c b/PDP11/pdp11_rq.c
index f5b1d0f6..26ffcfc5 100644
--- a/PDP11/pdp11_rq.c
+++ b/PDP11/pdp11_rq.c
@@ -1023,7 +1023,7 @@ DEVICE rq_dev = {
 MSC rqb_ctx = { 1 };
 
 DIB rqb_dib = {
-    IOBA_FLOAT, IOLN_RQ, &rq_rd, &rq_wr,
+    IOBA_AUTO, IOLN_RQ, &rq_rd, &rq_wr,
     1, IVCL (RQ), 0, { &rq_inta }
     };
 
@@ -1095,7 +1095,7 @@ DEVICE rqb_dev = {
 MSC rqc_ctx = { 2 };
 
 DIB rqc_dib = {
-    IOBA_FLOAT, IOLN_RQ, &rq_rd, &rq_wr,
+    IOBA_AUTO, IOLN_RQ, &rq_rd, &rq_wr,
     1, IVCL (RQ), 0, { &rq_inta }
     };
 
@@ -1167,7 +1167,7 @@ DEVICE rqc_dev = {
 MSC rqd_ctx = { 3 };
 
 DIB rqd_dib = {
-    IOBA_FLOAT, IOLN_RQ, &rq_rd, &rq_wr,
+    IOBA_AUTO, IOLN_RQ, &rq_rd, &rq_wr,
     1, IVCL (RQ), 0, { &rq_inta }
     };
 
diff --git a/PDP11/pdp11_vh.c b/PDP11/pdp11_vh.c
index 2fa14719..b3ef0dda 100644
--- a/PDP11/pdp11_vh.c
+++ b/PDP11/pdp11_vh.c
@@ -345,7 +345,7 @@ static t_stat vh_show_log (FILE *st, UNIT *uptr, int32 val, void *desc);
 #define IOLN_VH         020
 
 static DIB vh_dib = {
-    IOBA_FLOAT,
+    IOBA_AUTO,
     IOLN_VH * VH_MUXES,
     &vh_rd,     /* read */
     &vh_wr,     /* write */
diff --git a/PDP11/pdp11_xu.c b/PDP11/pdp11_xu.c
index 7d873dbe..ba7c7b36 100644
--- a/PDP11/pdp11_xu.c
+++ b/PDP11/pdp11_xu.c
@@ -198,7 +198,7 @@ DEVICE xu_dev = {
 
 #define IOLN_XU         010
 
-DIB xub_dib = { IOBA_FLOAT, IOLN_XU, &xu_rd, &xu_wr,
+DIB xub_dib = { IOBA_AUTO, IOLN_XU, &xu_rd, &xu_wr,
 		1, IVCL (XU), 0, { &xu_int } };
 
 UNIT xub_unit[] = {
diff --git a/VAX/vax610_defs.h b/VAX/vax610_defs.h
index dc0353a4..a30bb395 100644
--- a/VAX/vax610_defs.h
+++ b/VAX/vax610_defs.h
@@ -190,7 +190,6 @@ typedef struct {
 /* Qbus I/O page layout - see pdp11_ui_lib.c for address layout details */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 
 /* The KA610 maintains 4 separate hardware IPL levels, IPL 17 to IPL 14;
diff --git a/VAX/vax630_defs.h b/VAX/vax630_defs.h
index 50b740f6..0da5f090 100644
--- a/VAX/vax630_defs.h
+++ b/VAX/vax630_defs.h
@@ -235,7 +235,6 @@ typedef struct {
 /* Qbus I/O page layout - see pdp11_ui_lib.c for address layout details */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 
 /* The KA620/KA630 maintains 4 separate hardware IPL levels, IPL 17 to IPL 14;
diff --git a/VAX/vax730_defs.h b/VAX/vax730_defs.h
index 8bdfe5c2..4f7a0668 100644
--- a/VAX/vax730_defs.h
+++ b/VAX/vax730_defs.h
@@ -234,7 +234,6 @@ typedef struct {
 /* Unibus I/O page layout - see pdp11_ui_lib.c for address layout details */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 /* Interrupt assignments; within each level, priority is right to left */
 
diff --git a/VAX/vax750_defs.h b/VAX/vax750_defs.h
index 69d24f78..2fa1a551 100644
--- a/VAX/vax750_defs.h
+++ b/VAX/vax750_defs.h
@@ -270,7 +270,6 @@ typedef struct {
    Massbus devices (RP, TU) do not appear in the Unibus IO page */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 
 /* Interrupt assignments; within each level, priority is right to left */
diff --git a/VAX/vax780_defs.h b/VAX/vax780_defs.h
index a59431ba..d6a0074a 100644
--- a/VAX/vax780_defs.h
+++ b/VAX/vax780_defs.h
@@ -288,7 +288,6 @@ typedef struct {
    Massbus devices (RP, TU) do not appear in the Unibus IO page */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 
 /* Interrupt assignments; within each level, priority is right to left */
diff --git a/VAX/vax860_defs.h b/VAX/vax860_defs.h
index 810aedd4..4c1c80e1 100644
--- a/VAX/vax860_defs.h
+++ b/VAX/vax860_defs.h
@@ -322,7 +322,6 @@ typedef struct {
    Massbus devices (RP, TU) do not appear in the Unibus IO page */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 
 /* Interrupt assignments; within each level, priority is right to left */
diff --git a/VAX/vaxmod_defs.h b/VAX/vaxmod_defs.h
index 806d4e82..143ba631 100644
--- a/VAX/vaxmod_defs.h
+++ b/VAX/vaxmod_defs.h
@@ -285,7 +285,6 @@ typedef struct {
 /* Qbus I/O page layout - see pdp11_ui_lib.c for address layout details */
 
 #define IOBA_AUTO       (0)                             /* Assigned by Auto Configure */
-#define IOBA_FLOAT      (0)                             /* Assigned by Auto Configure */
 
 
 /* The KA65x maintains 4 separate hardware IPL levels, IPL 17 to IPL 14;