Windows: System-Locked Pre-installation (SLP)

System-Locked Pre-installation (SLP) is the mechanism used by OEM computer manufacturers to factory activate pre-installed Windows operating systems. There are now three different version of SLP:

  • SLP 1.0 for Windows XP and Windows Server 2008
  • SLP 2.0 for Windows Vista and Windows Server 2008
  • SLP 2.1, Windows 7, Windows Server 2008 R2, and has backward-compatibility support for Windows Vista and Windows Server 2008

For OEM activation to work and able to authenticate OEM licensing for Windows, three components or criteria must exist and fulfill:

  • Full SLIC table in BIOS
  • OEM certificate (xrm-ms) which corresponds with OEMID and OEMTableID (Windows Marker) in SLIC table
  • OEM-SLP product key

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