diff --git a/bit-ops.c b/bit-ops.c
index 03e7b97..24014bc 100644
--- a/bit-ops.c
+++ b/bit-ops.c
@@ -76,6 +76,13 @@ void do_arbitrary_stuff() {
 	PTCD |= 0xc0;
 	printf("PTCD |= 1110 0000 --> %#010x (", PTCD);
 	gimme_bin_int(PTCD);
+
+	printf("----------\n* set 0th bit to 0\n");
+	printf("PTCD = %u (", PTCD=0x5d);
+	gimme_bin_int(PTCD);
+	PTCD |= 0x50;
+	printf("PTCD |= 0x00 --> %#x (", PTCD);
+	gimme_bin_int(PTCD);
 }