Warp wrote:
>   With the z80 you can have 16-bit literals, perform 16-bit ALU operations
> (such as additions, substractions, shifts, etc), you can address the entire
> memory with one single 16-bit register, etc. I don't understand what's *not*
> 16-bit about the z80.

OK. I must be confusing the Z80 with the 8080, perhaps. I know the 8080 
had no 16-bit registers except PC and SP.  HL was two registers, for 
example.

>   Just because the 16-bit operations are performed on pairs of 8-bit
> registers that doesn't make it any less of a 16-bit operation.

OK. I guess we're just disagreeing about whether that ability makes a 
CPU an "8-bit CPU" or a "16-bit CPU".

I mean, I've used mainframes with "string" type opcodes that would 
operate on 1KBytes at a time. That wouldn't really make them a KByte 
CPU. :-)

>> Almost everyone calls the processor the number of bits on the data bus, 
>> fwiw, when talking about this stuff.
> 
>   How is that even useful?

Very useful for hardware type people. Also unambiguous. Plus, I didn't 
claim it was useful. I merely said it's what I noticed when I read all 
the literature.

Maybe because the "definitive" literature written by places like Intel 
are generally addressing people who build motherboards for their chips 
and such.

>   I understand "8-bit" to mean "has 8-bit registers, and you can only
> perform an 8-bit operation with a single opcode, because registers can
> only hold 8 bits of data". Likewise for any other bitsize.

Well, the 6502 had 16-bit absolute jumps, IIRC. I wouldn't call it a 
16-bit CPU.

>   Btw, didn't the 386 usually have a 16-bit data bus? The 386 is still
> a 32-bit processor, though.

I don't remember the bus size. But at this point, I think we're more 
arguing what you call the CPU than anything real about the CPU.

-- 
Darren New / San Diego, CA, USA (PST)
  Helpful housekeeping hints:
   Check your feather pillows for holes
    before putting them in the washing machine.

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