diff --git a/PDP11/pdp11_rk.c b/PDP11/pdp11_rk.c
index f434e480..84d0cedd 100644
--- a/PDP11/pdp11_rk.c
+++ b/PDP11/pdp11_rk.c
@@ -350,7 +350,6 @@ void rk_clr_done (void);
 t_stat rk_boot (int32 unitno, DEVICE *dptr);
 t_stat rk_help (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, const char *cptr);
 t_stat rk_attach (UNIT *uptr, CONST char *cptr);
-t_stat rk_detach (UNIT *uptr);
 const char *rk_description (DEVICE *dptr);
 
 DEBTAB rk_deb[] = {
@@ -419,7 +418,7 @@ DEVICE rk_dev = {
     "RK", rk_unit, rk_reg, rk_mod,
     RK_NUMDR, 8, 24, 1, 8, RKWRDSZ,
     NULL, NULL, &rk_reset,
-    &rk_boot, &rk_attach, &rk_detach,
+    &rk_boot, &rk_attach, NULL,
     &rk_dib, DEV_DISABLE | DEV_UBUS | DEV_Q18 | DEV_DEBUG | RK_DIS | DEV_DISK, 0,
     rk_deb, NULL, NULL, &rk_help, NULL, NULL,
     &rk_description, NULL, &drv_tab
@@ -906,12 +905,6 @@ return sim_disk_attach_ex2 (uptr, cptr, RK_NUMWD * sizeof (uint16),
                             RK_RSRVSEC);
 }
 
-t_stat rk_detach (UNIT *uptr)
-{
-sim_cancel (uptr);
-return sim_disk_detach (uptr);
-}
-
 /* Device bootstrap */
 
 #if defined (UC15) || !defined (VM_PDP11)
diff --git a/PDP11/pdp11_rl.c b/PDP11/pdp11_rl.c
index 04724707..45b956cd 100644
--- a/PDP11/pdp11_rl.c
+++ b/PDP11/pdp11_rl.c
@@ -1027,7 +1027,6 @@ return SCPE_OK;
 
 t_stat rl_detach (UNIT *uptr)
 {
-sim_cancel (uptr);
 uptr->STAT = RLDS_BHO | RLDS_LOAD;
 return sim_disk_detach (uptr);
 }
diff --git a/PDP11/pdp11_rx.c b/PDP11/pdp11_rx.c
index 74528feb..be5632b5 100644
--- a/PDP11/pdp11_rx.c
+++ b/PDP11/pdp11_rx.c
@@ -137,7 +137,6 @@ t_stat rx_rd (int32 *data, int32 PA, int32 access);
 t_stat rx_wr (int32 data, int32 PA, int32 access);
 t_stat rx_svc (UNIT *uptr);
 t_stat rx_attach (UNIT *uptr, CONST char *cptr);
-t_stat rx_detach (UNIT *uptr);
 t_stat rx_reset (DEVICE *dptr);
 t_stat rx_boot (int32 unitno, DEVICE *dptr);
 void rx_done (int32 esr_flags, int32 new_ecode);
@@ -206,7 +205,7 @@ DEVICE rx_dev = {
     "RX", rx_unit, rx_reg, rx_mod,
     RX_NUMDR, 8, 20, 1, 8, 8,
     NULL, NULL, &rx_reset,
-    &rx_boot, &rx_attach, &rx_detach,
+    &rx_boot, &rx_attach, NULL,
     &rx_dib, DEV_DISABLE | DEV_UBUS | DEV_QBUS | DEV_DISK, 0,
     NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, &drv_tab
     };
@@ -507,12 +506,6 @@ return sim_disk_attach (uptr, cptr, RX_NUMBY,
                      "RX01", 0, 0);
 }
 
-t_stat rx_detach (UNIT *uptr)
-{
-sim_cancel (uptr);
-return sim_disk_detach (uptr);
-}
-
 /* Device bootstrap */
 
 #define BOOT_START      02000                           /* start */
diff --git a/PDP11/pdp11_ry.c b/PDP11/pdp11_ry.c
index b46fab15..6f366ac7 100644
--- a/PDP11/pdp11_ry.c
+++ b/PDP11/pdp11_ry.c
@@ -169,7 +169,6 @@ t_stat ry_boot (int32 unitno, DEVICE *dptr);
 void ry_done (int32 esr_flags, uint8 new_ecode);
 t_stat ry_show_density (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
 t_stat ry_attach (UNIT *uptr, CONST char *cptr);
-t_stat ry_detach (UNIT *uptr);
 t_stat ry_help (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, const char *cptr);
 const char *ry_description (DEVICE *dptr);
 
@@ -246,7 +245,7 @@ DEVICE ry_dev = {
     "RY", ry_unit, ry_reg, ry_mod,
     RX_NUMDR, DEV_RDX, 20, 1, DEV_RDX, 8,
     NULL, NULL, &ry_reset,
-    &ry_boot, &ry_attach, &ry_detach,
+    &ry_boot, &ry_attach, NULL,
     &ry_dib, DEV_DISABLE | DEV_DISI | DEV_UBUS | DEV_Q18 | DEV_DISK, 0,
     NULL, NULL, NULL, &ry_help, NULL, NULL,
     &ry_description, NULL, &drv_tab
@@ -602,12 +601,6 @@ return sim_disk_attach_ex (uptr, cptr, uptr->drvtyp->sectsize,
                            NULL);
 }
 
-t_stat ry_detach (UNIT *uptr)
-{
-sim_cancel (uptr);
-return sim_disk_detach (uptr);
-}
-
 /* Show density */
 
 t_stat ry_show_density (FILE *st, UNIT *uptr, int32 val, CONST void *desc)
diff --git a/PDP11/pdp11_td.c b/PDP11/pdp11_td.c
index 684928f3..07a7d8bd 100644
--- a/PDP11/pdp11_td.c
+++ b/PDP11/pdp11_td.c
@@ -645,7 +645,6 @@ static t_stat td_set_ctrls (UNIT *uptr, int32 val, CONST char *cptr, void *desc)
 static t_stat td_show_ctlrs (FILE *st, UNIT *uptr, int32 val, CONST void *desc);
 static t_stat td_boot (int32 unitno, DEVICE *dptr);
 static t_stat td_attach (UNIT *uptr, CONST char *cptr);
-static t_stat td_detach (UNIT *uptr);
 static t_stat td_help (FILE *st, DEVICE *dptr, UNIT *uptr, int32 flag, const char *cptr);
 static void tdi_set_int (int32 ctlr, t_bool val);
 static int32 tdi_iack (void);
@@ -720,7 +719,7 @@ DEVICE tdc_dev = {
     "TDC", td_unit, td_reg, td_mod,
     2*TD_NUMCTLR, DEV_RDX, 20, 1, DEV_RDX, 8,
     NULL, NULL, &td_reset,
-    &td_boot, &td_attach, &td_detach,
+    &td_boot, &td_attach, NULL,
     &td_dib, DEV_DISABLE | DEV_DIS | DEV_UBUS | DEV_QBUS | DEV_DEBUG | DEV_DISK, 0,
     td_deb, NULL, NULL, &td_help, NULL, NULL,
     &td_description, NULL, &drv_tab
@@ -1523,12 +1522,6 @@ return sim_disk_attach (uptr, cptr, TD_NUMBY,
                         "TU58", 0, 0);
 }
 
-static t_stat td_detach (UNIT *uptr)
-{
-sim_cancel (uptr);
-return sim_disk_detach (uptr);
-}
-
 /* Device bootstrap */
 
 #if defined (VM_PDP11)