[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Innovative Systems Floating Point Engine Rev B 1988
Mike Westerfield wrote:
On Aug 4, 7:19 am, "Yvan" <yvan_d...@gmx.net> wrote:
Hi,
I found a Innovative Systems Floating Point Engine Rev B 1988.
First, what is it? Can I use it in my IIgs? Do I need any software or
drivers? Are there any documentations anywhere?
Cheers
Yvan
Hi Yvan,
There is a software patch that allows this card to intercept and
handle any calculation normally routed through the SANE numerics
package. That works pretty well, but there is significant overhead--
enough that some calculations are about as fast in software. (Not all,
and not the more complex calculations.)
That's been my experience with math coprocessors.
Trig functions and SQR are big wins (since their software
implementations are so slow), but the simple ops, like add
and subtract, are at best a wash.
There are also compiler directives for the ORCA languages that will
bypass SANE and tap directly into the card itself. This is
considerably more efficient, and works for long integer math as well
as floating-point. It turned out that short integer math takes less
time in software than the overhead of using the card, so the ORCA
languages do not use the card for short integers.
All in all, it's a great card if you intend to do any number-
crunching, especially in software you write. Congratulations on
finding one.
The problem with most math coprocessors is that they require lots of
overhead moving operands in and out of the card. A DMA-based
coprocessor might help a lot more.
In comparisons done on a //e, I find that a math-heavy mix of operations
are speeded up by a math coprocessor just about as much as by an 8MHz
Zip Chip--with which most math coprocessors are incompatible (because
they use the RDY line to stall the 6502 and the Zip Chip doesn't
implement it).
Since the Zip Chip speeds up everything and the math coprocessor only
speeds up multiply, divide, and functions, the Zip Chip wins. ;-)
I don't know whether this math coprocessor is compatible with a IIgs
accelerator, but that would be something to check...
-michael
AppleCrate: An Apple II "blade server"!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it's seriously underused."