Re: Keeping other stuff with addresses (was: What is an N-bit machine?)

On Sun, 1 Dec 2024 17:53:19 -0000 (UTC)
Thomas Koenig <tkoenig@netcologne.de> wrote:

Tim Rentsch <tr.17687@z991.linuxsc.com> schrieb:

Thomas Koenig <tkoenig@netcologne.de> writes:
 

I think "ALU can add up to n-bit numbers" is a reasonable
definition for an n-bit architecture, which also fits the 16-bit
68000. It does not fit the 360/30, or the Nova (but see de
Castro's remark on the latter). 

>
To me, the phrase "n-bit architecture" should depend only on such
characteristics as are defined by the architecture, and not depend
on features of a particular implementation.  The 360/30 has a 32-bit
(or is it 64-bit?) architecture, but only an 8-bit implementation.
>
If I may add a personal note, it's disappointing that postings in a
group nominally devoted to computer architecture routinely ignore
the distinction between architecture and implementation. 

 
I'm well aware of that distinction.
 
On the other hand, I have right before me a book with the title
"MC68000 16-BIT MICROPROCESSOR User's manual third edition", ISBN
0-13-566695-3 (in paperback).   One may argue that the authors
of that book didn't know what they were writing about (since the
68000 has a 32-bit ISA), but I would try to define the terms in
such a way that this is also included.

IMHO, the authors of the book are wrong. At least as long as were are
talking about current meaning of the bitness. It is possible that 40
years ago the word had different meaning. But I find more likely that
it had no established meaning.