Look at the referenced IBM docs: They included the actual schematics of the adapters. I don't know if they are 100% complete, but even so, that level of technical detail is almost unimaginable now.<p>(I hope the link works, otherwise, see e.g. page 19=28).<p><a href="https://archive.org/details/bitsavers_ibmpccardsptionsandAdaptersVolume2Apr84_25079400/page/n27/mode/2up?view=theater" rel="nofollow">https://archive.org/details/bitsavers_ibmpccardsptionsandAda...</a>