Additionally, the 8086 is not much like the 386! And the 386 isn't much like the 486, which differed surprisingly from the Pentium. And each subsequent revision

Additionally, the 8086 is not much like the 386! And the 386 isn't much like the 486, which differed surprisingly from the Pentium. And each subsequent revision has followed this trend of being (at the very least) different enough from its predecessors that assembly language programmers need to re-read the manuals. Today we even have a 64-bit version, which differs from its trail of 32-bit ancestors even more than they differed from one another...