Why is the Zilog Z80 considered to be an 8 bit processor?

>>59630370
afaik to be called an n-bit processor the operand size must be n bits
are there some operations that only allow 8-bit operands?

>>59630370
Because it has 8-bit registers.

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acc reg is 8bit so all ops are 8bit.

>>59630410
>are there some operations that only allow 8-bit operands?
Some of the arithmetic operations are 8 bit only, but it sounds like 16 bit versions of those operations are easily doable in software with just a couple extra steps.

>>59630567
While A and A' are 8 bit accumulators, HL and HL' are 16 bit accumulators. IX and IY can also be used as 16 bit accumulators according to Wikipedia. Is simply having accumulators A and A' that aren't 16 bit enough for the processor to not be considered 16 bit?

>>59630806
>Some of the arithmetic operations are 8 bit only
This is probably the reason. I'm guessing to qualify for a 16-bit architecture all operations must allow 16-bit operands
>but it sounds like 16 bit versions of those operations are easily doable in software with just a couple extra steps.
That is true for pretty much any architecture

>>59630370
>>59631148
On looking a bit further, it seems the problem is that the Z80 doesn't have a 16 bit internal data bus. The Intel 8088 still has a 16 bit internal data bus, even though it has an 8 bit external data bus. What operations the processor is capable off performing apparently isn't considered.