The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: Tony Williams
Subject: Re: Calculator math processor (like the MM57109)
Date: Wed, 11 Dec 2002 13:25:33 +0000 (GMT)
NNTP-Posting-Date: Wed, 11 Dec 2002 13:25:40 +0000 (UTC)
User-Agent: Pluto/1.14i (RISC-OS/3.60)
In article <3DF72BBC.15B79976@redrok.com>,
Duane C. Johnson wrote:
> 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
Good Lord! I used an MM7109, no supporting uP,
just a programme counter and EPROM. No RAM even,
all numbers held on the 57019's stack.
Worked like a dream... the software inspector
initially would not believe that a programme
that small could be doing it all.
But then it went obsolete. They did make a
replacement, but it was unsuitable for us.
> 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.
AFAIR the MM57109 was itself no more than a masked
microprocessor. So something similar could be done
in a PIC..... a lot of work though, especially the
trig functions. I think though the trig functions
in the 57109 were done with not-very-large lookup
tables and interpolation. Forth groups will often
still have information on doing this sort of thing.
> OK, wouldn't it be neat to find one with an I2C interface!
Better maybe to use a uP with a large enough ROM,
have a library of FP arithmetic subroutines and just
compile whatever is required, on a job by job basis.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup