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From: "Duane C. Johnson"
Subject: Calculator math processor (like the MM57109)
Date: Wed, 11 Dec 2002 06:12:44 -0600
Organization: Red Rock Energy http://www.redrok.com
X-Mailer: Mozilla 4.77 [en] (Win95; U)
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.
I'm investigating in this method so I can use relatively
simple PIC micros with limited memory capabilities.
OK, wouldn't it be neat to find one with an I2C interface!
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