diff --git a/HP2100/hp2100_dp.c b/HP2100/hp2100_dp.c
index 3b3f2bcc..196cbac8 100644
--- a/HP2100/hp2100_dp.c
+++ b/HP2100/hp2100_dp.c
@@ -695,7 +695,7 @@ void dp_goc (int32 fnc, int32 drv, int32 time)
 {
 int32 t;
 
-t = sim_is_active (&dpc_unit[drv]);
+t = sim_activate_time (&dpc_unit[drv]);
 if (t) {                                                /* still seeking? */
     sim_cancel (&dpc_unit[drv]);                        /* stop seek */
     dpc_sta[drv] = dpc_sta[drv] & ~STA_BSY;             /* clear busy */
diff --git a/HP2100/hp2100_dq.c b/HP2100/hp2100_dq.c
index 4ca85689..816c7bf7 100644
--- a/HP2100/hp2100_dq.c
+++ b/HP2100/hp2100_dq.c
@@ -531,7 +531,7 @@ void dq_goc (int32 fnc, int32 drv, int32 time)
 {
 int32 t;
 
-t = sim_is_active (&dqc_unit[drv]);
+t = sim_activate_time (&dqc_unit[drv]);
 
 if (t) {                                                /* still seeking? */
     sim_cancel (&dqc_unit[drv]);                        /* cancel */
diff --git a/HP2100/hp2100_stddev.c b/HP2100/hp2100_stddev.c
index edf44c2c..50f42081 100644
--- a/HP2100/hp2100_stddev.c
+++ b/HP2100/hp2100_stddev.c
@@ -1021,7 +1021,7 @@ int32 sync_poll (POLLMODE poll_mode)
 int32 poll_time;
 
     if (poll_mode == INITIAL) {
-        poll_time = sim_is_active (&tty_unit[TTI]);
+        poll_time = sim_activate_time (&tty_unit[TTI]);
 
         if (poll_time)
             return poll_time;
diff --git a/HP2100/hp_disclib.c b/HP2100/hp_disclib.c
index ea51945e..d6320e82 100644
--- a/HP2100/hp_disclib.c
+++ b/HP2100/hp_disclib.c
@@ -772,7 +772,7 @@ else if (uptr) {                                        /* otherwise, we have a
     uptr->wait = cvptr->cmd_time;                       /* most commands use the command delay */
 
     if (props->unit_access) {                           /* does the command access the unit? */
-        is_seeking = sim_is_active (uptr) != 0;         /* see if the unit is busy */
+        is_seeking = sim_activate_time (uptr) != 0;     /* see if the unit is busy */
 
         if (is_seeking)                                 /* if a seek is in progress, */
             uptr->wait = 0;                             /*   set for no unit activation */
diff --git a/Interdata/id_uvc.c b/Interdata/id_uvc.c
index 7ccc070a..0d1d9451 100644
--- a/Interdata/id_uvc.c
+++ b/Interdata/id_uvc.c
@@ -358,7 +358,7 @@ int32 lfc_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&lfc_unit);
+t = sim_activate_time (&lfc_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/PDP1/pdp1_clk.c b/PDP1/pdp1_clk.c
index 9e3914fd..acc32533 100644
--- a/PDP1/pdp1_clk.c
+++ b/PDP1/pdp1_clk.c
@@ -89,7 +89,7 @@ int32 used, incr;
 
 if (clk_dev.flags & DEV_DIS)                            /* disabled? */
     return (stop_inst << IOT_V_REASON) | dat;           /* illegal inst */
-used = tmxr_poll - (sim_is_active (&clk_unit) - 1);
+used = tmxr_poll - (sim_activate_time (&clk_unit) - 1);
 incr = (used * CLK_CNTS) / tmxr_poll;
 return clk_cntr + incr;
 }
diff --git a/PDP10/pdp10_tim.c b/PDP10/pdp10_tim.c
index c15cd503..883f085d 100644
--- a/PDP10/pdp10_tim.c
+++ b/PDP10/pdp10_tim.c
@@ -154,7 +154,7 @@ tempbase[1] = tim_base[1];
 if (tim_mult != TIM_MULT_T20) {                         /* interpolate? */
     int32 used;
     d10 incr;
-    used = tmr_poll - (sim_is_active (&tim_unit) - 1);
+    used = tmr_poll - (sim_activate_time (&tim_unit) - 1);
     incr = (d10) (((double) used * TIM_HW_FREQ) /
         ((double) tmr_poll * (double) clk_tps));
     tim_incr_base (tempbase, incr);
@@ -219,7 +219,7 @@ int32 t;
 
 if (tim_mult == TIM_MULT_T20)
     return wait;
-t = sim_is_active (&tim_unit);
+t = sim_activate_time (&tim_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/PDP10/pdp10_tu.c b/PDP10/pdp10_tu.c
index 6be277b8..52867de4 100644
--- a/PDP10/pdp10_tu.c
+++ b/PDP10/pdp10_tu.c
@@ -1015,7 +1015,7 @@ return;
 
 void update_tucs (int32 flag, int32 drv)
 {
-int32 act = sim_is_active (&tu_unit[drv]);
+int32 act = sim_activate_time (&tu_unit[drv]);
 
 if ((flag & ~tucs1) & CS1_DONE)                         /* DONE 0 to 1? */
     tuiff = (tucs1 & CS1_IE)? 1: 0;                     /* CSTB INTR <- IE */
diff --git a/PDP11/pdp11_rl.c b/PDP11/pdp11_rl.c
index 107b8077..25802bee 100644
--- a/PDP11/pdp11_rl.c
+++ b/PDP11/pdp11_rl.c
@@ -1093,7 +1093,7 @@ t_stat rl_show_dstate (FILE *st, UNIT *uptr, int32 val, void *desc)
         (uptr->STAT & RLDS_WGE) ? '1' : '0',
         (uptr->STAT & RLDS_SPE) ? '1' : '0');
     if (uptr->flags & UNIT_ATT) {
-        if ((cnt = sim_is_active (uptr)) != 0)
+        if ((cnt = sim_activate_time (uptr)) != 0)
             fprintf (st, "FNC: %d, %d\n", uptr->FNC, cnt);
         else
             fputs ("FNC: none\n", st);
diff --git a/PDP11/pdp11_stddev.c b/PDP11/pdp11_stddev.c
index c20a0168..8166a285 100644
--- a/PDP11/pdp11_stddev.c
+++ b/PDP11/pdp11_stddev.c
@@ -462,7 +462,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/PDP11/pdp11_tu.c b/PDP11/pdp11_tu.c
index d0ced0a9..3a763c90 100644
--- a/PDP11/pdp11_tu.c
+++ b/PDP11/pdp11_tu.c
@@ -822,7 +822,7 @@ return;
 
 void tu_update_fs (int32 flg, int32 drv)
 {
-int32 act = sim_is_active (&tu_unit[drv]);
+int32 act = sim_activate_time (&tu_unit[drv]);
 
 tufs = (tufs & ~FS_DYN) | FS_FPR | flg;
 if (tu_unit[drv].flags & UNIT_ATT) {
diff --git a/VAX/vax610_stddev.c b/VAX/vax610_stddev.c
index 6e421d73..fd10cd83 100644
--- a/VAX/vax610_stddev.c
+++ b/VAX/vax610_stddev.c
@@ -402,7 +402,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/VAX/vax630_stddev.c b/VAX/vax630_stddev.c
index 713766ff..a68ec5c1 100644
--- a/VAX/vax630_stddev.c
+++ b/VAX/vax630_stddev.c
@@ -338,7 +338,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/VAX/vax730_stddev.c b/VAX/vax730_stddev.c
index 293afaeb..5b72844c 100644
--- a/VAX/vax730_stddev.c
+++ b/VAX/vax730_stddev.c
@@ -854,7 +854,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/VAX/vax750_stddev.c b/VAX/vax750_stddev.c
index 8b6e3a90..d97dc57e 100644
--- a/VAX/vax750_stddev.c
+++ b/VAX/vax750_stddev.c
@@ -855,7 +855,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/VAX/vax780_stddev.c b/VAX/vax780_stddev.c
index ec576050..a3bf1669 100644
--- a/VAX/vax780_stddev.c
+++ b/VAX/vax780_stddev.c
@@ -672,7 +672,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/VAX/vax_stddev.c b/VAX/vax_stddev.c
index 2d98e3f7..8ae46489 100644
--- a/VAX/vax_stddev.c
+++ b/VAX/vax_stddev.c
@@ -410,7 +410,7 @@ int32 clk_cosched (int32 wait)
 {
 int32 t;
 
-t = sim_is_active (&clk_unit);
+t = sim_activate_time (&clk_unit);
 return (t? t - 1: wait);
 }
 
diff --git a/VAX/vax_sysdev.c b/VAX/vax_sysdev.c
index 52a57221..4884ecba 100644
--- a/VAX/vax_sysdev.c
+++ b/VAX/vax_sysdev.c
@@ -1464,7 +1464,7 @@ return;
 
 void tmr_sched (int32 tmr)
 {
-int32 clk_time = sim_is_active (&clk_unit) - 1;
+int32 clk_time = sim_activate_time (&clk_unit) - 1;
 int32 tmr_time;
 
 tmr_sav[tmr] = sim_grtime ();                           /* save intvl base */
diff --git a/sigma/sigma_mt.c b/sigma/sigma_mt.c
index 7e3e9f35..61fb423b 100644
--- a/sigma/sigma_mt.c
+++ b/sigma/sigma_mt.c
@@ -278,7 +278,7 @@ t_mtrlnt tbc;
 t_stat r;
 
 if (cmd == MCM_INIT) {                                  /* init state */
-    if ((t = sim_is_active (uptr + MT_REW)) != 0) {     /* rewinding? */
+    if ((t = sim_activate_time (uptr + MT_REW)) != 0) { /* rewinding? */
         sim_activate (uptr, t);                         /* retry later */
         return SCPE_OK;
         }