Here is a rabbit hole for your consideration! The PDP-8 had an optional card set called the EAE for Extended Arithmetic Element. These cards performed asynchronous math calculations as described in the attached screenshot. Better yet, the coding manual and circuit diagrams are available online here:
http://vandermark.ch/pdp8/index.php?n=H ... Arithmetichttp://vandermark.ch/pdp8/uploads/Hardw ... awings.pdfOn the circuit diagrams I see some standard TTL glue logic, counters, multiplexers and some ROMs. I attached a photo of the boards from the links. The circuit diagrams are especially interesting. If you have any other links I'd enjoy seeing them. Thanks!