more work on Mega65 native mode

src/kernal/iostack/seldev.s

@@ -0,0 +1,21 @@
+// #LAYOUT# STD *        #TAKE
+// #LAYOUT# *   KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+SELDEV:
+
+	// Take last device number, make sure it is a drive - 8 or above. Above 30,
+	// although illegal for IEC we also consider a drive, as they exists
+	// drivers assigning these numbers to CBM-DOS capable devices - like some
+	// IEEE-488 carts.
+	//
+	// If current device is not a drive, set device to 8 (first drive number)
+	// Device number is left in X, for SETFLS Kernal routine
+
+	ldx FA
+	cpx #$08
+	bcs !+
+	ldx #$08
+!:
+	rts