Re: [stella] RAM Cart?

Subject: Re: [stella] RAM Cart?
From: Mark De Smet <desmet@xxxxxxxxxxxx>
Date: Tue, 19 Jan 1999 13:23:41 -0600 (CST)
> >Another interesting technology that would be useful for RAM carts is an
> >with internal battery backup. Dallas Semi-conductor (and I am sure other 

> Huh? Built-in battery? Is this a rechargeable or a one-way battery?

Single use, rechargeables have an even shorter life.

> I mean, if the battery's discharged, and you can't exchange it, you have to
> discard the whole chip!

True, but they undoubtedly have refined the whole backup to require so
little current it doesn't matter.  A modern CMOS SRAM can hold the data
and use less than 0.01uA.  A AA battery has enough power to last about
5000 years at that rate.  The battery would go bad because of it's shelf
life first, which if lithium would be at least 10yrs.  As pointed out, the
chip isn't that expensive, and depending on the battery backup circuit you
build yourself is a cheaper alternative.(I spent $10 on just a battery for
my circuit, which I could replace, but don't expect to have to, ever)

The really cool thing to do would be to use a 'super cap' 1F capacitor.
Then it would never go bad, but would require being used(put in atari and
turned on) every so often to hold the data.


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