Tuesday, November 17, 2009 10:05 PM,

A student writes:



	 Good Evening Dr. Patt,
	 
	 just 2 quick questions:
	 
	 Can you ONLY write to the DDR? 
	 
	 Also, Is this correct for clarification:
	 
	 KBSR, KBDR, and DSR can both be written to and read from?
	 
	 Thanks so much for your time,
	 <<name withheld to protect a student who finds it easier to write than 
	 think>>
 


I am happy to answer this for you.  BUT, first, a few questions for you: 

What is DDR?
Does it make sense to read from it and write to it?
What about the other three device registers?

Please yourself the question for each device register: 
Does it make sense to read from it and write to it?  
After you have thought about this for ten minutes, and if you still have these 
questions, send me email and I will answer them.

Good luck on the exam tomorrow.

Yale Patt