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Intel 80286 CPU Errata: A1 and B1 Steppings

[The following information is from an undated 15-page Intel document titled “Undocumented iAPX 286 Test Instruction”, p. 15]

Early versions of the 80286 have several errata items which may effect the implementation of software to emulate an 8086/8088 on a protected mode 80286 or expansion of the address space in real mode. These errata are in the A1 and B1 steppings of the 80286 and are fixed in later steppings of the 80286.