Does that mean you would count AL, AH, but not AX (as it can be split into AL/AH and doesn't "bring new bits"), and then again would count EAX and RAX?
However if I were doing emulation, I would have to count it because it is a register case that has to be addressed. Just like the D register has to be dealt with on a 6809.
My own personal way to resolve this has always been to determine whether or not a given register specification, that can be addressed somehow, brings new information not contain in any other register specification, to the table.
Fact is, CPU designers do all kinds of crazy things with registers. They overlap, they may be indirect, like not directly addressable, but still there as consideration for the programmer.
Think about something like the REP instruction found on some CPUs. There's a little circuit it keeps track of account, and some rules, and account may be a register that may or may not be directly addressable any other way.
My general take on this article is, "wow, that's a lot of registers!"
We can all quibble about what the quantity of a lot is, and it's all good fun, and I don't think it means anything really.
