diff --git a/atx_avr.h b/atx_avr.h
index f25fed3..5414e84 100644
--- a/atx_avr.h
+++ b/atx_avr.h
@@ -19,4 +19,4 @@
 //
 //*****************************************************************************
 
-#define NUM_ATX_DRIVES 2
\ No newline at end of file
+#define NUM_ATX_DRIVES 3	//for drive 0-2, D0 is needed for the sdrive control program