[TenTec] Paragon 2 Memory Battery Back-up

[Dr. Gerald N. Johnson]

Without having done it, I suppose one would cut the 5.6 volt power to 
the processor chip pin 40, insert a schottky diode for minimal voltage 
drop, then hook up a 6 volt chargeable battery (charged from the 
unregulated 13 volts) through a plain silicon diode to that same pin 40. 
4 NiCad cells should hold the micro for a long time, might not need to 
be chargeable, just a couple 3 volt Li Cells, like 2032 in series to 
make 6 volts. When power was on the battery diode would be reverse 
biased, when power was off the schottky diode would be reverse biased 
and the battery would keep the processor supplied with power. Likely it 
takes a lot more power to hold up the processor than the processor's 
memory alone. I can't tell from the schematic what the processor number 
is, it shows the same MC146803EP2 part on a 40 pin and a 16 pin package. 
What is it really (Paragon II)?

73, Jerry, K0CQ