diff --git a/20211115/blink-0a.c b/20211115/blink-0a.c
new file mode 100644
index 0000000000000000000000000000000000000000..45e90fe4568e357cc9342a0d7369be6312a83e64
--- /dev/null
+++ b/20211115/blink-0a.c
@@ -0,0 +1,9 @@
+#include <avr/io.h>
+
+int main (void)
+{
+  DDRD = 0xff;   /* binär: 1111 1111 */
+  PORTD = 0x40;  /* binär: 0100 0000 */
+  while (1);
+  return 0;
+}
diff --git a/20211115/blink-2.c b/20211115/blink-2.c
index b00eaf522563b1e8fa75f80e784de5b9f1af58e9..9389b19b1bf46d5ca90bac823e3f94269fe02878 100644
--- a/20211115/blink-2.c
+++ b/20211115/blink-2.c
@@ -5,7 +5,7 @@
 
 int main (void)
 {
-  DDRD = 0x02;
+  DDRD = 0x02;  /* binär: 0000 0010 */
   PORTD = 0x02;
   while (1)
     {
diff --git a/20211115/blink-2a.c b/20211115/blink-2a.c
new file mode 100644
index 0000000000000000000000000000000000000000..a226654a35eb061364dab1cf6a035eb6c5dd4df0
--- /dev/null
+++ b/20211115/blink-2a.c
@@ -0,0 +1,16 @@
+#include <avr/io.h>
+
+#define F_CPU 16000000l
+#include <util/delay.h>
+
+int main (void)
+{
+  DDRD = 0x02;  /* binär: 0000 0010 */
+  PORTD = 0x02;
+  while (1)
+    {
+      _delay_ms (500);
+      PORTD = PORTD ^ 0x02;
+    }
+  return 0;
+}
diff --git a/20211115/blink-2b.c b/20211115/blink-2b.c
new file mode 100644
index 0000000000000000000000000000000000000000..90ed36c2f976050b898458e3efd6b818ecf8e775
--- /dev/null
+++ b/20211115/blink-2b.c
@@ -0,0 +1,16 @@
+#include <avr/io.h>
+
+#define F_CPU 16000000l
+#include <util/delay.h>
+
+int main (void)
+{
+  DDRB = 1 << 5;
+  PORTB = 1 << 5;
+  while (1)
+    {
+      _delay_ms (500);
+      PORTB ^= 1 << 5;
+    }
+  return 0;
+}
diff --git a/20211115/blink-4.c b/20211115/blink-4.c
index 7344aa7ce19086d6e0a0dc4f8de78499f280931b..ceafab6b1e7462497fde98b7a12e72cc34132bbe 100644
--- a/20211115/blink-4.c
+++ b/20211115/blink-4.c
@@ -5,11 +5,11 @@
 
 int main (void)
 {
-  DDRD = 0x01;
-  PORTD = 0x01;
-  while (1)
+  DDRD = 0x01;   /* binär: 0000 0001 */
+  PORTD = 0x01;  /*                ^ Ouptut */
+  while (1)      /*               ^ Input   */
     {
-      while ((PIND & 0x02) == 0)
+      while ((PIND & 0x02) == 0)  /* binär: 0000 0010 */
         ; /* just wait */
       PORTD ^= 0x01;
       _delay_ms (200);
diff --git a/20211115/int-types-1.c b/20211115/int-types-1.c
new file mode 100644
index 0000000000000000000000000000000000000000..832e6c5fccce8279368fcbe5b0a4ea14b7854e9b
--- /dev/null
+++ b/20211115/int-types-1.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint64_t x = 42;
+  printf ("Die Antwort lautet: %d\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-2.c b/20211115/int-types-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..0f1cef1b9d244fc2c0db06903438857b65dd9330
--- /dev/null
+++ b/20211115/int-types-2.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %d\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-3.c b/20211115/int-types-3.c
new file mode 100644
index 0000000000000000000000000000000000000000..caa58838a6c400455217de68994376393c8677f7
--- /dev/null
+++ b/20211115/int-types-3.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %ld\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-4.c b/20211115/int-types-4.c
new file mode 100644
index 0000000000000000000000000000000000000000..572dba1af722084d815c04eeb27750c4149e22f4
--- /dev/null
+++ b/20211115/int-types-4.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %lld\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-5.c b/20211115/int-types-5.c
new file mode 100644
index 0000000000000000000000000000000000000000..1d41e53bad5636cce6ddf23ace59d3a92427b6d5
--- /dev/null
+++ b/20211115/int-types-5.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %"
+          "ld"
+          "\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-6.c b/20211115/int-types-6.c
new file mode 100644
index 0000000000000000000000000000000000000000..dd04eaaf323d51a325111606bad2bf1a45201f4b
--- /dev/null
+++ b/20211115/int-types-6.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %" PRIu64 "\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-7.c b/20211115/int-types-7.c
new file mode 100644
index 0000000000000000000000000000000000000000..42acfc38e362dc89de762c7675cf192aec170b69
--- /dev/null
+++ b/20211115/int-types-7.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include <inttypes.h>
+
+int main (void)
+{
+  printf ("Die Formatspezifikation lautet: %s\n", PRIu64);
+  return 0;
+}
diff --git a/20211115/int-types-7.txt b/20211115/int-types-7.txt
new file mode 100644
index 0000000000000000000000000000000000000000..15df839deaef480abf5d5b324ea75b400026b13f
--- /dev/null
+++ b/20211115/int-types-7.txt
@@ -0,0 +1,15 @@
+#include <stdio.h>
+#include <inttypes.h>
+
+int main (void)
+{
+  printf ("Die Formatspezifikation lautet: %s\n", PRIu64);
+  return 0;
+}
+cassini/home/peter/bo/2021ws/hp/20211115> gcc -m32 -Wall -O int-types-7.c -o int-types-7
+cassini/home/peter/bo/2021ws/hp/20211115> ./int-types-7
+Die Formatspezifikation lautet: llu
+cassini/home/peter/bo/2021ws/hp/20211115> gcc -Wall -O int-types-7.c -o int-types-7
+cassini/home/peter/bo/2021ws/hp/20211115> ./int-types-7
+Die Formatspezifikation lautet: lu
+cassini/home/peter/bo/2021ws/hp/20211115>
diff --git a/20211115/int-types-8.c b/20211115/int-types-8.c
new file mode 100644
index 0000000000000000000000000000000000000000..0bd4ad7f0141922998f8f68393b6a9cd22431c3b
--- /dev/null
+++ b/20211115/int-types-8.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %" PRIx64 "\n", x);
+  return 0;
+}
diff --git a/20211115/int-types-9.c b/20211115/int-types-9.c
new file mode 100644
index 0000000000000000000000000000000000000000..bb987ef6792361669aee636f47d1a075bb6c8a4b
--- /dev/null
+++ b/20211115/int-types-9.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <inttypes.h>
+
+int main (void)
+{
+  uint64_t x = 42000000000;
+  printf ("Die Antwort lautet: %016" PRIx64 "\n", x);
+  return 0;
+}