Questions on the LC3.5 ISA 
CS352H-ers,

One more:

> How should the nzp registers be set for the load operations?  

In general any instruction that writes the register file should set
the NZP bits according to the register being written into the register
file.  Thus for a load, you actually have to wait to see what value
comes back from memory.  For the purposes of this problem, just set
NZP according to the output of the ALU.

> jsrr is
> not defined in the .h file, should we be doing something for that?

Note that the JSR and JSRR have the same opcode (top 4 bits) but
differ in the 5th bit from the top.  For the purposes of the ALU, you
don't need to distinguish between them.

> Also, trap is defined in the .h file but what operation needs to be
> done for that?

Trap should produce a 16-bit result with the top 8 bits set to zero
and the bottom 8 bits set to the bottom 8 bits of the IR.  Recall that
the TRAP instruction indexes into the trap vector (stored in memory)
to fetch the next PC to jump to.


Cheers,

Steve Keckler                     Computer Architecture and Technology Lab
Assistant Professor               Tel:    (512) 471-9763
Department of Computer Sciences   Dept:   (512) 471-7316
1 University Station C0500        Fax:    (512) 232-1413
The University of Texas at Austin E-mail:  skeckler@cs.utexas.edu
Austin, TX 78712-1188             http://www.cs.utexas.edu/users/skeckler
                                  


