Check out the Dallas or Maxim DS1210 or Maxim MAX1210.  This chip handles
switching power from the main supply to one of two batteries (I'm using a
capacitor for backup power).  You also route the chip select line thru
the chip.  This disables reads and writes when the main power is gone.

Harold



Harold Hallikainen
harold@hallikainen.com
Hallikainen & Friends, Inc.
See the FCC Rules at http://hallikainen.com/FccRules and comments filed
in LPFM proceeding at http://hallikainen.com/lpfm

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