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Old 6th Oct 2017, 7:48 am   #6
Dave Moll
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Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,118
Default Re: "Genie" telephone

I did think to have a go at tracing out the circuit, as there's not too much in the way of discrete components outside the three chips. The problem I've encountered, though, is that I can only find datasheets for two of the chips. The one I can't find is labelled:

MEDL 8721
ZMA522PO

Presumably, this is a custom chip. Would that "PO" at the end signify "Post Office" by any chance?
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