diff --git a/NOVA/nova_tt.c b/NOVA/nova_tt.c
index 5d362833..b79503f0 100644
--- a/NOVA/nova_tt.c
+++ b/NOVA/nova_tt.c
@@ -193,7 +193,7 @@ return SCPE_OK;
 t_stat tti_reset (DEVICE *dptr)
 {
 tmxr_set_console_units (&tti_unit, &tto_unit);
-tti_unit.buf = 0;                                       /* <not DG compatible>  */
+tti_unit.buf = 0;                                       /* <not DG compatible> */
 DEV_CLR_BUSY( INT_TTI ) ;
 DEV_CLR_DONE( INT_TTI ) ;
 DEV_UPDATE_INTR ;
diff --git a/PDP1/pdp1_cpu.c b/PDP1/pdp1_cpu.c
index 2a8eea73..bca59e33 100644
--- a/PDP1/pdp1_cpu.c
+++ b/PDP1/pdp1_cpu.c
@@ -25,7 +25,7 @@
 
    cpu          PDP-1 central processor
 
-   27-Mar-15    RMS     Backported changed from GitHub master
+   27-Mar-15    RMS     Backported changes from GitHub master
    21-Mar-12    RMS     Fixed & vs && in Ea_ch (Michael Bloom)
    30-May-07    RMS     Fixed typo in SBS clear (Norm Lastovica)
    28-Dec-06    RMS     Added 16-channel SBS support, PDP-1D support
diff --git a/sigma/sigma_coc.c b/sigma/sigma_coc.c
index 5f4826d0..97f4bf4b 100644
--- a/sigma/sigma_coc.c
+++ b/sigma/sigma_coc.c
@@ -24,7 +24,6 @@
    in this Software without prior written authorization from Robert M Supnik.
 
    coc          7611 communications multiplexor
-
 */
 
 #include "sigma_io_defs.h"
diff --git a/sigma/sigma_io_defs.h b/sigma/sigma_io_defs.h
index 875cfaa6..6dedd093 100644
--- a/sigma/sigma_io_defs.h
+++ b/sigma/sigma_io_defs.h
@@ -194,7 +194,7 @@ typedef struct {
 #define DVA_CP          0x004
 #define DVA_PT          0x005
 #define DVA_MUX         0x006
-#define DIO_MUX         0x3
+#define DIO_MUX         0x003
 #define DVA_MT          0x080
 #define DVA_RAD         0x180
 #define DVA_DK          0x190