diff --git a/eeprom.c b/eeprom.c
index ed81a3f..02caf20 100755
--- a/eeprom.c
+++ b/eeprom.c
@@ -124,6 +124,9 @@ void eeprom_put_char( unsigned int addr, unsigned char new_value )
 	sei(); // Restore interrupt flag state.
 }
 
+// Extensions added as part of Grbl 
+
+
 void memcpy_to_eeprom_with_checksum(unsigned int destination, char *source, unsigned int size) {
   unsigned char checksum = 0;
   for(; size > 0; size--) { 
diff --git a/script/console b/script/console
index 17a86ca..5eeac80 100755
--- a/script/console
+++ b/script/console
@@ -1,4 +1,4 @@
-socat -d -d READLINE /dev/tty.usbmodem26221,nonblock=1,clocal=1
+socat -d -d READLINE /dev/tty.usbmodem24121,nonblock=1,clocal=1
 socat -d -d READLINE /dev/tty.usbserial-A9007QcR,clocal=1,nonblock=1,cread=1,cs8,ixon=1,ixoff=1
 
 #socat -d -d READLINE /dev/tty.FireFly-A964-SPP-1,clocal=1,nonblock=1,cread=1,cs8,ixon=1,ixoff=1
diff --git a/stepper.c b/stepper.c
index 840272e..b867017 100644
--- a/stepper.c
+++ b/stepper.c
@@ -32,7 +32,12 @@
 #include "stepper_plan.h"
 #include "wiring_serial.h"
 
-void set_step_events_per_minute(uint32_t steps_per_minute);
+
+// Some useful constants
+#define STEP_MASK ((1<<X_STEP_BIT)|(1<<Y_STEP_BIT)|(1<<Z_STEP_BIT)) // All step bits
+#define DIRECTION_MASK ((1<<X_DIRECTION_BIT)|(1<<Y_DIRECTION_BIT)|(1<<Z_DIRECTION_BIT)) // All direction bits
+#define STEPPING_MASK (STEP_MASK | DIRECTION_MASK) // All stepping-related bits (step/direction)
+#define LIMIT_MASK ((1<<X_LIMIT_BIT)|(1<<Y_LIMIT_BIT)|(1<<Z_LIMIT_BIT)) // All limit bits
 
 #define ENABLE_STEPPER_DRIVER_INTERRUPT()  TIMSK1 |= (1<<OCIE1A)
 #define DISABLE_STEPPER_DRIVER_INTERRUPT() TIMSK1 &= ~(1<<OCIE1A)
@@ -72,6 +77,8 @@ static uint32_t trapezoid_adjusted_rate;      // The current rate of step_events
 //  The slope of acceleration is always +/- block->rate_delta and is applied at a constant rate by trapezoid_generator_tick()
 //  that is called ACCELERATION_TICKS_PER_SECOND times per second.
 
+void set_step_events_per_minute(uint32_t steps_per_minute);
+
 // Initializes the trapezoid generator from the current block. Called whenever a new 
 // block begins.
 inline void trapezoid_generator_reset() {