Update explanation

diff --git a/natanael/ex09/Explanation.txt b/natanael/ex09/Explanation.txt
index 16ffe39..a0ee64e 100644 (file)
--- a/natanael/ex09/Explanation.txt
+++ b/natanael/ex09/Explanation.txt
@@ -5,3 +5,4 @@ ex9a2
 The dummy task has a higher priority than the task which handle the interupt. But when the interupt is trigged, it will run the interupt first as the urgency and it become priority 257.
 
 ex9b
+Firstly, we need to enable the interupt from the parallel port. Every key press in the parallel port, it will increase the counter. 
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