I often get questions from PMP aspirants on memorizing input, output, tool & technique from various knowledge areas. They often ask about an easy way to remember/memorize all those input, output, tool & technique.
Before I explain a method to memorize, let me reveal one thing. I did not try to memorize all those input, output, tool & technique. I tried to understand those and the flows. I felt pretty comfortable during the exam.
Beware, there are around 10-20 questions directly formed from input, output, tool & technique. So it is imperative that you understand them. But you don't really have to memorize them.
However, you may follow the method that I suggest, if you really want to memorize all of them and don't want to miss even a single question incorrectly answered during the exam.
First finish your text book readings from PMBOK, Rita and Kim Heldman. Kim has the flow in a great manner. Take the first mock exam. Till this point do not dare to memorize the input, output, tool & technique. After your first mock exam. You would have a fair idea of what these all about and their flow. Now try to memoize and write down on paper while keeping your books closed. Try writing down a few times during your prep time.
Identify the weak areas and jot down on the rough paper they give at the start of the exam. That will come as handy during the exam.
Remember, to pass the exam, you don't have to memorize everything.