Re: 6502 illegal opcodes questions

["mdj" <mdj.mdj@gmail.com>]

Michael J. Mahon wrote:

> > It's probably a combination of obstinacy and caution. On todays
> > hardware, you can do some pretty amazing numerics on GPU's rather than
> > CPU's, which have orders of magnitude more computational power than
> > CPU's with regards to numerical calculations. Getting it *right* for
> > numerics is hard, and given the rate of change in the hardware arena
> > thus far, it may prove to be more sensible to have left it until the
> > dust settles a little.
>
> Whoops--cop out.  There is essentially universal agreement on IEEE
> FP, with the only holdouts being...LANGUAGE DESIGNERS!  It's at least
> a decade past time to get with the program!

Here's the changes that actually were made to the Language
Specification for version 1.2.

http://java.sun.com/docs/books/jls/strictfp-changes.pdf

In essence, these changes relax the rules on floating point arithmetic
for intermediate calculations, meaning you can take advantage of the
peculiarities of particular fp engine implementations (the Intel 80 bit
implementation being the primary example cited) at the cost of
non-reproducability of results across Java implementations, which
nobody seems to care about.

There's a strictfp keyword that exists to enforce the original
reproducable semantics for cases where it's required, which it would
seem, is almost never, I've not seen any code actually use it.

This edition of the platform was released in 1999, so it seems the
major issue went away with those changes.

What remains to be done is an extension to handle richer numerics, like
complex numbers. 

Matt