CDCE/Xtend MC32 Memory Expansion
U8 - Lattice GAL 20V8
U9, 11, 23 - Signetics "Plus" 173BA (programmable logic array)
RP4, RP5 - Resistor networks (RP4 made by Bourns, RP5 unknown)
JP1 - Unknown, set as shown. (May be used to select between IBM presence detect coding and "industry standard" presence detect coding?)
The Xtend variant of this card (pictured at mcamafia.de, under the 7430 ADF download link) appears to be no different than this one.
This is a very simple card. I'd hazard a guess (without having run it yet) that this will give you 16MB RAM maximum in machines like the Models 70 and 80. It should take parity SIMMs from between 70 to 85ns.