From: Spehro Pefhany
Subject: Re: Calculator math processor (like the MM57109)
X-Newsreader: Forte Agent 1.92/32.572
Date: Wed, 11 Dec 2002 14:40:29 GMT
NNTP-Posting-Date: Wed, 11 Dec 2002 09:40:29 EST
On Wed, 11 Dec 2002 06:12:44 -0600, the renowned "Duane C. Johnson"
>I have an application that is math intensive but doesn't
>need to operate quickly. The math involves astronomical
>calculations so will use trig functions. Cost and low power
>Many years ago I used a neat chip from National Semiconductor
>called an MM57109. This chip was a full scientific calculator
>with a digital interface instead of a more common keyboard
>interface. I had a CD1802 development computer from Netronics
>that used it to make a pretty good Basic program.
>I have 5 of these chips but they are now antiques.
>Two are in a calculator made by National Semiconductor.
>I understand the Intel 8231 and AMD 9511 worked in a similar
>way. I have not used these though.
>Anyway I'm looking for a modern version.
>I'm having a difficult time finding any companies that sell
>just the calculator chips. I could possibly fashion an
>interface that looks like a keyboard and LCD.
Buy a microcontroller of your choice, and a compiler, and
you can make as many as you want. Check the FP support
carefully before shelling out for the compiler, especially
cheap compilers. Some, such as GCC that targets the AVR
are free. Performance will be much better than that
old NMOS chip, and power consumption much lower.
Then, if you want to do sin(x), just ask (and be prepared
for a couple K or more of library functions to be linked
into your object code the first time you ask for a trig
floating point function, and #include math.h if you are
using C). Make sure to choose a processor family that
includes members with enough code memory in particular,
just in case you get tight. The PIC 14 or 16 bit
architectures, AVR, and 8051 all would be suitable.
Of course you could always implement those functions
from first principles in assembler, research the best
algorithms and probably would end up with a better
tailored solution, but you might have better things
to do with a few months of your life.
"it's the network..." "The Journey is the reward"
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