1.
a)
                            ...   ...   
                          ______________
                         |___IR_________|
                                     |
                                     |
             ------------------------o       
            |                        | 
            |                        |   
         ___|__                      | 
        |skip  |                     | 
        |______|             nop     |
            |  _________         |   |
            | | ___    |  ___    |   |
            | o|   \   | |   | __|___|____
            |  |    )--o-|D Q|-\_1___0___/
            |--|___/     |   |     |
   clock-----------------|>  |     |
                         |___|     |     
                                   |
                                   |                        
                         ...   ...   
                         
                         
b)
If there is a bubble after the skip instruction, the bubble will be skipped
and the next invalid instruction that should be skipped will not be skipped.
IF the flipflop use the interclock as its clock, stall will not cause any
problem. Because flipflop stores the skip information, and when the next 
instruction comes, it will be skipped.

c)
IF the branch instruction is followed by a skip instuction and 
skip is after IF stage, then the skip information will be stored
in the flipflop and it will cause the first instruction branched to
being skipped.  

2.
	-- ALUa          ALUb          memory      control
            -             -         Rt = 0;         - 
            -             -         Ri = 1;         - 
     LP:    -             -         Ra = a[Ri];     - 
            -             -         Rb = b[Ri];     - 
         - = Ra * Rb;     -             -           - 
        Ra = Rt + Ra;     -             -           - 
        Rt = ---------    _	        -	    -	
                          -         Ri = Ri + 1;    - 
            -             -         Ra = Ri + -10;  - 
	    -             -             -       if Ra < 0, goto LP;
	    


Optimized:
	    
        -- ALUa          ALUb          memory      control
	    -             -         Rt = 0;         - 
            -             -         Ri = 1;         - 
            -             -         Rj = 10;        - 
            -             -         R1 = 1;         - 
            -         Rj = Rj - R1; Ra = a[Ri];     - 
            -         Ri = Ri + R1; Rb = b[Ri];     - 

     LP:Rt = Ra * Rb; Rj = Rj - R1; Ra = a[Ri];     - 
        Rc = Rt + Rc; Ri = Ri + R1; Rb = b[Ri]; if Rj > 0, goto LP;
        
        Rt = Ra * Rb;     -             -           - 
        Rc = Rt + Rc;     -             -           -	    
        Rt = ---          -             -           - 
        
3.
Active record:
    _________
   |_________|FIB2  = 4
   |_________|FIB1  = 3 
   |_________|VALUE = 2
   |_________|CP    = 1
   |_________|DL    = 0
    
   AR: R1
   NR: R2
   RA: R3
   I : R4 --store the parameter i
   
---calling sequence

	load-address NR AR 5

	store I NR VALUE

---save registers to *AR

	load RA R0 2 

	load R0 R0 0

	FIB

---restore registers from *AR

------------------------

---receiving sequence
FIB:

	store RA AR CP

	store AR NR DL

	load-address AR NR 0

------------------------
---return sequence
	
	load AR AR DL
	
	load RA AR CP
	
	load-address R0 RA 0