diff --git a/I1620/i1620_pt.c b/I1620/i1620_pt.c
index 25b2626b..acfd1cf1 100644
--- a/I1620/i1620_pt.c
+++ b/I1620/i1620_pt.c
@@ -81,8 +81,11 @@ UNIT ptr_unit = {
 REG ptr_reg[] = {
     { FLDATAD (BIN, ptr_mode, 0, "binary mode flag") },
     { DRDATAD (POS, ptr_unit.pos, T_ADDR_W, "position in the input file"), PV_LEFT },
-    { DRDATAD (TIME, ptr_unit.wait, 24, "reader character delay"), PV_LEFT },
+#if (SIM_MAJOR >= 4)
     { DRDATAD (CPS, ptr_unit.DEFIO_CPS, 24, "Character Input Rate"), PV_LEFT },
+#else
+    { DRDATAD (TIME, ptr_unit.wait, 24, "reader character delay"), PV_LEFT },
+#endif
     { NULL }
     };
 
@@ -108,8 +111,11 @@ UNIT ptp_unit = {
 REG ptp_reg[] = {
     { FLDATAD (BIN, ptp_mode, 0, "binary mode flag") },
     { DRDATAD (POS, ptp_unit.pos, T_ADDR_W, "position in the output file"), PV_LEFT },
-    { DRDATAD (TIME, ptp_unit.wait, 24, "punch character delay"), PV_LEFT },
+#if (SIM_MAJOR >= 4)
     { DRDATAD (CPS, ptp_unit.DEFIO_CPS, 24, "Character output rate"), PV_LEFT },
+#else
+    { DRDATAD (TIME, ptp_unit.wait, 24, "punch character delay"), PV_LEFT },
+#endif
     { NULL }
     };
 
diff --git a/I1620/i1620_tty.c b/I1620/i1620_tty.c
index 619e5436..8b5ec77e 100644
--- a/I1620/i1620_tty.c
+++ b/I1620/i1620_tty.c
@@ -98,10 +98,13 @@ REG tty_reg[] = {
     { FLDATAD (UNLOCK, tti_unlock, 0, "keyboard unlocked flag") },
     { FLDATAD (FLAG, tti_flag, 0, "set flag on next input digit"), REG_HRO },
     { DRDATAD (COL, tto_col, 7, "current column") },
-    { DRDATAD (KTIME, tty_unit[UTTI].wait, 24, "keyboard polling interval"), REG_NZ + PV_LEFT },
-    { DRDATAD (TTIME, tty_unit[UTTO].wait, 24, "typewriter character delay"), REG_NZ + PV_LEFT },
+#if (SIM_MAJOR >= 4)
     { DRDATAD (CPS, tty_unit[UTTO].DEFIO_CPS, 24, "Character Output Rate"), PV_LEFT },
     { DRDATAD (ICPS, tty_unit[UTTI].DEFIO_CPS, 24, "Character Input Rate"), PV_LEFT },
+#else
+    { DRDATAD (KTIME, tty_unit[UTTI].wait, 24, "keyboard polling interval"), REG_NZ + PV_LEFT },
+    { DRDATAD (TTIME, tty_unit[UTTO].wait, 24, "typewriter character delay"), REG_NZ + PV_LEFT },
+#endif
     { NULL }
     };
 
@@ -502,7 +505,7 @@ return SCPE_OK;
 
 t_stat tty_reset (DEVICE *dptr)
 {
-sim_activate (&tty_unit[UTTI], tty_unit[UTTI].wait);    /* activate poll */
+DEFIO_ACTIVATE(&tty_unit[UTTI]);                        /* activate poll */
 sim_cancel (&tty_unit[UTTO]);                           /* cancel output */
 tti_unlock = tti_flag = 0;                              /* tty locked */
 tto_col = 1;
diff --git a/doc/i1620_doc.doc b/doc/i1620_doc.doc
index ff66fb86..154bd9a1 100644
Binary files a/doc/i1620_doc.doc and b/doc/i1620_doc.doc differ