diff --git a/C64_4joy_adapter/README.md b/C64_4joy_adapter/README.md
index 9349d34..79aefb9 100644
--- a/C64_4joy_adapter/README.md
+++ b/C64_4joy_adapter/README.md
@@ -31,6 +31,7 @@ sei
 - in can load from io to register
 - out can write from register to io
 - only one io/data address space access within one instruction?
+- lds/sts takes 2 cycles and in/out takes 1 cycle?
 
 ## avr asm
 - http://www.nongnu.org/avr-libc/user-manual/inline_asm.html