diff --git a/PDP10/pdp10_defs.h b/PDP10/pdp10_defs.h
index 126e5504..643f4eb5 100644
--- a/PDP10/pdp10_defs.h
+++ b/PDP10/pdp10_defs.h
@@ -621,6 +621,8 @@ typedef struct pdp_dib DIB;
 
 #define DZ_MUXES        4                               /* max # of muxes */
 #define DZ_LINES        8                               /* lines per mux */
+#define KMC_UNITS       1                               /* max # of KMCs */
+#define INITIAL_KMCS    0                               /* Number initially enabled */
 #define DUP_LINES       4                               /* max # of DUP11's */
 #define DIB_MAX         100                             /* max DIBs */
 
diff --git a/PDP11/pdp11_defs.h b/PDP11/pdp11_defs.h
index 9fde51a3..3f4c4157 100644
--- a/PDP11/pdp11_defs.h
+++ b/PDP11/pdp11_defs.h
@@ -483,6 +483,8 @@ typedef struct {
 #define DLX_LINES       16                              /* max # of KL11/DL11's */
 #define DCX_LINES       16                              /* max # of DC11's */
 #define DUP_LINES       8                               /* max # of DUP11/DPV11's */
+#define KMC_UNITS       2                               /* max # of KMC11s */
+#define INITIAL_KMCS    0                               /* Number to initially enable */
 #define MT_MAXFR        (1 << 16)                       /* magtape max rec */
 #define DIB_MAX         100                             /* max DIBs */