At least he admits he is a last minute questioner, although in pre-empting my "privilege" to assign him a signature line, he demonstrates either lack of spelling acumen or lack of understanding the difference between one who questions, and a list of questions.

Oh, well, anything to prepare him for the midterm. To wit:

     I know this is kind of last minute so it might not be answered
     befor the test, but i was studying tonight and reading over notes
     and saw that my TA went over how many memory accesses a command has,
     like trap x22, or LEA etc. What exactly is considered a memory access?
     Is it taking a value out of a register.  I know that fetch is always
     considered a memory access, but i am unsure if you were to ask, how
     many memory accesses are in LEA, if we include fetch as one, and what
     is the rule for when we inclue fetch? Sorry for the last minute
     question and for not knowing something i can tell is extremely simple.

     << Last minute questionaire >>

So, then: A memory access is an access of memory. Each one requires MAR to be loaded with an address, and memory told either "gimme" (i.e., load from memory into MDR) or "here" (i.e., store from MDR into memory).

Yes, instruction fetch is a memory access, because PC is loaded into MAR and then the contents of memory are read.

No, accessing a register is not a memory access, it is a register access. MAR is not even breathed on, let alone touched.


Good luck on the exam tomorrow.

Yale Patt