6

### Reading Assignment and Discussion Topics

Computer Science 471

*for class on
Tuesday
Oct. 1, 1996*

Please read
Sections 4.6 through 4.12
of the Patterson & Hennessy text,
and be prepared to discuss the following issues:

**1.**
What would a floating-point multiply circuit look like?
Let's make one in the style of Figure 4.42.
Figure 4.43 purports to describe floating-point multiplication,
but is instead just a copy of Figure 4.42.
The correct version of Figure 4.43 can be found at
http://www.cs.princeton.edu/courses/cs471/fig4-43.gif.
An *integer*-style multiplier will be
needed somewhere in the
middle of our circuit; we will not work on the
insides of this.
Single precision, IEEE format.
Your instructor is always a little shakey on *rounding*
and *overflow*; any help you can give him
with this will be appreciated.

**2.**
Famous Princeton guy John von Neumann is quoted on
pages 293-4 of the text
expressing arguments for and against floating point.
A page of the 50-year-old document in which these quotes appear is
reproduced on
http://www.cs.princeton.edu/courses/cs471/vonN.gif;
the relevant part is Section 5.3.
What do you think
of von Neumann's original arguments and why did
he decide this issue the way he did? (And what are these
``scale factors,'' anyway?) Was he wrong? Was he wrong *then*?