-- INSTRUCTION EXECUTION PROECURE AND LOAD/STORE PROCEDURE --



The CPU will wait for the outside world to tell it that the load or store
is complete before it does anything else (including loading a 16-bit
instructions or half of a 32-bit instruction).  Basically, the CPU will
wait until the outside world sets the "data_ready" CPU input high.  

The CPU also lets the outside world know when it wants to read or write
through its "req_rdwr" output.









Data Loading/Storing Procedure Part 1:
  * The CPU sets "req_rdwr" to high, "data_acc_sz" to the size of the
  load (0 for 8-bit load, 1 for 16-bit load), and "data_inout_we" to 0.
Data Loading/Storing Procedure Part 2:
  * The CPU waits for the outside world to set the CPU input called
  "data_ready" to high.  This may take more than one cycle depending on how
  quickly the outside world can deal with the request.  On the SAME cycle
  that "data_ready" is set to high, the CPU WILL start doing something
  else, such as executing a loaded instruction.



Instruction Execution Procedure (assuming no interrupts or resets happen):
  * NOTE that ON THE CYCLE BEFORE AN INSTRUCTION IS STARTED, Data
  Loading/Storing Procedure Part 1 (Start a 16-bit Load of a 16-bit
  Instruction or 16-bit Load of the high 16 bits of a 32-bit instruction)
  is performed.


16-bit instructions that DON'T do an 8-bit load or store:
  * Data Loading/Storing Procedure Part 2 is performed (Finish a 16-bit
  Load of a 16-bit Instruction).
  * The instruction is executed.  Also, perform Data Loading/Storing
  Procedure Part 1 (Start a 16-bit Load of a 16-bit Instruction or the high
  16 bits of a 32-bit Instruction).



16-bit instructions that DO do an 8-bit load or store:
  * Data Loading/Storing Procedure Part 2 is performed (Finish a 16-bit
  Load of a 16-bit Instruction).
  * Start executing the instruction:  Data Loading/Storing Procedure Part 1
  is performed (Start an 8-bit Load or Store).
  * Finish executing the instruction:  Data Loading/Storing Procedure Part
  2 is performed (Finish an 8-bit Load or Store).  Also, perform Data
  Loading/Storing Procedure Part 1 (Start a 16-bit Load of a 16-bit
  Instruction or the high 16 bits of a 32-bit Instruction).


32-bit instructions that DON'T do an 8-bit load or store:
  * Data Loading/Storing Procedure Part 2 is performed (Finish a 16-bit
  Load of the HIGH 16 bits of a 32-bit instruction).
  * Data Loading/Storing Procedure Part 1 is performed (Start a 16-bit Load
  of the LOW 16 bits of a 32-bit instruction).
  * Data Loading/Storing Procedure Part 2 is performed (Finish a 16-bit Load
  of the LOW 16 bits of a 32-bit instruction).  On the same cycle, the
  instruction is executed.  Also, perform Data Loading/Storing Procedure
  Part 1 (Start a 16-bit Load of a 16-bit Instruction or the high 16 bits
  of a 32-bit Instruction).



32-bit instructions that DO do an 8-bit load or store:
  * Data Loading/Storing Procedure Part 2 is performed (Finish a 16-bit
  Load of the HIGH 16 bits of a 32-bit instruction).
  * Data Loading/Storing Procedure Part 1 is performed (Start a 16-bit Load
  of the LOW 16 bits of a 32-bit instruction).
  * Data Loading/Storing Procedure Part 2 is performed (Finish a 16-bit Load
  of the LOW 16 bits of a 32-bit instruction).
  * Start executing the instruction:  Data Loading/Storing Procedure Part 1 
  is performed (Start an 8-bit Load or Store).
  * Finish executing the instruction:  Data Loading/Storing Procedure Part 2
  is performed (Finish an 8-bit Load or Store).  Also, perform Data
  Loading/Storing Procedure Part 1 (Start a 16-bit Load of a 16-bit
  Instruction or the high 16 bits of a 32-bit Instruction).