Best links I’ve found:
bdos calls: http://www.shaels.net/index.php/cpm80-22-documents
https://www.seasip.info/Cpm/bdos.html
CPM3 for S100 http://www.s100computers.com/Software%20Folder/CPM3%20BIOS%20Installation/CPM3%20HDISK%20BIOS%20Software.htm
CPM3 https://forum.vcfed.org/index.php?threads/installing-cp-m-3-plus-on-a-home-built-z80-computer.61802/
ISIS/PLM https://www.retrotechnology.com/restore/isis.html
General info: http://primrosebank.net/computers/cpm/cpm_about.htm