Appendix H
Appendix H is the name of an infamous appendix in Pentium Processor Family Developer's Manual, Volume 3. This appendix contained reference to documentation only available under a legally binding NDA.
This NDAed documentation described various new features introduced in the Pentium processor, notably Virtual Mode Extensions and 4 MB paging. VME added an additional feature to the existing virtual 8086 mode that was introduced with the 80386 processor, and included optimized handling and delivery of interrupts to and from virtual machines.
The appendix was referenced by the official chapters in the documentation, provoking irritation among the public who was not allowed to access the detailed descriptions. This started a movement with observers trying to reverse-engineer the information in various ways. Notably, Robert Collins and Christian Ludloff played a major role in this.
