For new designs, or rewiring old ones (dead-bug?), is
there a generally
agreed logical substitute for the 8640?
--- The DEC8640 is recognized as the National Semiconductor DS8640, long obsolete of
course.
It is listed as being available here:
http://octopart.com/partsearch#!?q=ds8640
Most sources there quote by RFQ (which I have found does work) but one, Quest, has it for
$15.
Steve Lafferty