@7430.ADF Xtend 32MC Micro Channel Memory Expansion Board (unverified!)
C7430.ADF Initialization File (required!)
Based on content by William Walsh (original HERE).
JP1 Unknown (set as shown)
RP4,5 Resistor networks
U8 Lattice GAL 20V8
U9,11,23 Signetics Plus 173BA
JP1 Unknown (set as shown). May be used to select between IBM and "industry standard" presence detect coding?
The Xtend variant of this card (pictured HERE), appears to be no different than this one (aside from the silkscreen).
This is a very simple card. I'd hazard a guess that this will give you 16 MB RAM maximum in machines like the Models 70 and 80. It should take parity SIMMs from between 70 to 85 ns.