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A comment on Intel x86 documentation has more pages than the 6502 has transistors. Parent comment

Re:Intel x86 documentation has more pages than the 6502 has ... by Someone on Wednesday December 07, 2016 @05:52PM (#13127000)
According to http://www.pagetable.com/?p=364 (which also shows part of the reason the x86 needs so much documentation, by the way), it started its life "reserved", and never got a real role in life.
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Re:Intel x86 documentation has more pages than the 6502 has ... by yuubi on Thursday December 08, 2016 @01:15PM (#13132581)
Sounds like someone meant to use CR1 after CR0, but someone bit-swapped the CR-number bus so you have to encode 4 in the instruction to get 1 where it needs to go.
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Re:Intel x86 documentation has more pages than the 6502 has ... by bonzini on Thursday December 08, 2016 @03:53AM (#13129202)
Yes, but: "instead of overflowing the new bits into CR1, Intel decided to skip it and open up CR4 instead – for unknown reasons."
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Re:Intel x86 documentation has more pages than the 6502 has ... by vidarh on Thursday December 08, 2016 @04:36AM (#13129335)
Sounds like someone took "reserved" a bit too seriously and/or couldn't figure out who had marked it reserved or why, and decided the latter was the safer option.
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