Midterm 2 - Terms pg. 1

Question 1

How to know when overflow?

Answer 1

(+) + (+) = 1
(-) + (-) = 0

OR

(-) - (+) = 0
(+) - (-) = 1

Question 2

How to deal with overflow?

Answer 2

• ignore; let programmer handle it

* invoke exception handler

Question 3

“subword parallelism”:

Answer 3

performing multiple operations with a single ALU operation.

Question 4

SIMD:

Answer 4

Single Instruction, Multiple Data

Question 5

saturation:

Answer 5

if number too large, set equal to max value. if number to small, set equal to min value.

Question 6

“clipping” in audio, :

Answer 6

saturation in video!

Question 7

Software emulation:

Answer 7

Add a bunch times!

Question 8

Serial Multiplier hardware:

Answer 8

Add and Shift for each bit

Question 9

Parallel Multiplier hardware:

Answer 9

Many adders working together

Question 10

in MIPS, HI/LO regs. 32-bit multiply:

Answer 10

64-bit result!

* must move from HI/LO –> mfhi/mflo

Question 11

Long division approach:

Answer 11

if ( divisor <= dividend) 
* 1 in quotient, subtract divisor from dividend.
else.
* bring down next dividend bit.
Repeat.

Question 12

Hardware doesn’t know if less than, so…

Answer 12

must restore division if overflow occurs (remainder < 0)

Question 13

Signed division:

Answer 13

too hard. divide using absolute values, adjust sign as required

Question 14

Serial divider:

Answer 14

subtract and shift

Question 15

Parallel divider?

Answer 15

requires knowledge of previous bits, can’t fully parallelize

Question 16

MIPS division:

Answer 16

uses HI/LO regs for result.
HI = remainder
LO = quotient

Question 17

Signed division:

Answer 17

Negate quotient if signs are different