That was because LOADALL was impossible to preserve, since the internal state of the CPU changed in the next models.
80386 also had an undocumented LOADALL instruction, but it was encoded with a different opcode, as it was incompatible with the 80286 LOADALL, by restoring many more registers.
After 1990, no successors to LOADALL were implemented, because Intel introduced the "System Management Mode" instead, which provided similar facilities and much extra.
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That was because LOADALL was impossible to preserve, since the internal state of the CPU changed in the next models.
80386 also had an undocumented LOADALL instruction, but it was encoded with a different opcode, as it was incompatible with the 80286 LOADALL, by restoring many more registers.
After 1990, no successors to LOADALL were implemented, because Intel introduced the "System Management Mode" instead, which provided similar facilities and much extra.