### A good answer might be:

    11111 111
     1010 1011
     0101 0101
     ---------
     0000 0000
| Does overflow happen for: Unsigned Binary? Overflow -- The carry out is one. Two's Complement? In Range -- The carry in is the same as the carry out.

# The `addu` Instruction

The `addu` instruction performs the Binary Addition Algorithm on the contents of two 32-bit registers and places the result in the destination register. The destination register can be the same as one of the source registers. The `addu` instruction mechanically grinds through the Binary Addition Algorithm, producting a 32-bit result from two 32-bit operands. Overflow is ignored (that is what the "u" at then end of the mnemonic means).

    addu  d,s,t        # $d <-- s + t
                       # no overflow trap

There is another instruction, `add`, which causes a trap when two's complement overflow is detected. Other than that, it is the same as `addu`. A trap is an interruption in the normal machine cycle. Typically on a computer system a trap results in sending control back to the operating system.

    add   d,s,t        # $d <-- s + t
                       # with overflow trap

Most assembly programmers deal with overflow by making sure that the operands won't cause it. Usually they use the `addu` instruction. Until you know how to handle a trap that is the approach we will take.

### QUESTION 4:

What is the range of integers that can be represented with 32-bit two's complement?

    -2---- to +2-----1

(Pick an exponent for each "2").