diff --git a/src/devices/cpu/cop400/cop400.cpp b/src/devices/cpu/cop400/cop400.cpp
index 630a93866ae..1db85978414 100644
--- a/src/devices/cpu/cop400/cop400.cpp
+++ b/src/devices/cpu/cop400/cop400.cpp
@@ -50,6 +50,7 @@
     - COP410L/COP410C
     - save internal RAM when CKO is RAM power supply pin
     - COP404L opcode map switching, dual timer, microbus enable
+    - improve SIO output timing for interface with 93CXX serial EEPROMs
 
 */