I have a desktop system from an OEM that's not included in SLIC toolkit or other utilities. I know it has an SLP and must have at least SLIC 2.0 because the company shipped large numbers of computers with both Windows versions and even had their logo on the COA tags. So yes, a large company which would have their own SLP and SLIC codes in the BIOS but not recognized by the available utilities. I want to extract them from the last OEM BIOS and transplant (plus update to SLIC 2.1 or later) to the last BIOS released by the motherboard manufacturer. The board is made by Intel, same as the retail version but with the OEM BIOS. I have the OEMBIOS backup from XP but not from Vista, haven't been able to get an original Vista DVD for this OEM.
It's quite easy. For Vista activation you need to find a SLIC >=2.0. Use rw-everything and look for ACPITables on the particular machine. No SLIC table, no licensing for Vista. For SLP1.0 (XP) dump string address space (also with rw-everything) and search for a potential OEM string. Both has nothing to do with recognition. IF licensed then they are there for sure. DMI area (0xE0000-0xFFFFF) for SLP1.0 strings and ACPINamespace for all ACPITables and SLIC has to be one of them... Additionally decrypt the OEMBIOS files to find all valid ranges / strings...