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12902Re: [cosmacelf] Re: The 1802 Elf and Serial EEPROMs

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  • Lee Hart
    Mar 21, 2013
      On 3/21/2013 8:06 AM, jdrose_8_bit wrote:
      >> Another option is simply to battery back up your RAM, so it simply
      >> retains the data as long as the batteries last. With CMOS, this can be
      >> many years!

      > That is an interesting option. A CR2032 would probably be enough for a while. I am not much of an EE but I doubt that it would take a complicated circuit change to the PE ELF to do battery backup for the RAM.

      Indeed, it was in one of their original articles. The circuitry needed
      is little more than the RAM, two diodes, and a pullup resistor on the
      RAM's "write" pin so it won't accidentally float low.

      On the Membership Card, I found that I didn't even need the diodes. I
      could battery backup *everything*, and still hold data for a year on two
      AA cells.
      Anyone can make the simple complicated. Creativity is making the
      complicated simple. -- Charles Mingus
      Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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