diff --git a/projekte/attiny13/blink.asm b/projekte/attiny13/blink.asm
index 6250f6a..8db9579 100644
--- a/projekte/attiny13/blink.asm
+++ b/projekte/attiny13/blink.asm
@@ -9,6 +9,9 @@ loop:
 	cbi PORTB, 1
 
 ; wait
+; takes roughly ((2+2)*(256*256))/(9.6*1000*1000/8) ~ .218 seconds.
+; 2 cycles SBIW + 2 cycles BRNE for 256*256 subtractions
+; 9.6 MHz (CKSEL[1..0] = 10) with CKDIV=8
 loop1:
  	sbiw ZL, 1
 	brne loop1