Re: Macintosh LC...need info on this =) TIA

[pausch@saaf.se (Paul Schlyter)]

In article <3a2c6b0d@naylor.cs.rmit.edu.au>,
Matt Jenkins  <mdj@bilby.cs.rmit.edu.au> wrote:
 
> Paul Schlyter <pausch@saaf.se> wrote:
>> In article <3a2b2149@naylor.cs.rmit.edu.au>,
>> Matt Jenkins  <mdj@bilby.cs.rmit.edu.au> wrote:
>>  
>>> Roy and/or Janet Miller <millers@inetnebr.com> wrote:
>>>> frankc wrote:
>>> 
>>>>> I think to keep in the spirit of early Apple machines maybe we should
>>>>> service the needs of users of older Macs.  I do not own any newer Macs,
>>>>> but I do own some of the older 8/16 bits versions (Is the 68000 8-bit?)
>>> 
>>>> The 68000 is generally rated as a 16/32 bit chip (kinda like the 8088
>>>> was an 8/16 bit chip)
>>> 
>>> I think you mean 32/24 bit chip. The 68000 has real 32 bit instructions,
>>  
>> Yep -- 32-bit ADD/SUBTRACT but only 16-bit MULTIPLY/DIVIDE....
> 
> IIRC, 16 bit M/D with 32 bit result...
 
Just like the good ol' 8088, which too had 16x16 multiply yielding a
32-bt product.  It also had a 32 by 16 divide -- does that make the
8088 a 32-bit CPU?
 
BTW the 386, 486 and Pentiums have a 32x32 multiply yielding a 64-bit
result, and they have a 64 by 32 bit divide -- does that make these
chips 64-bit CPU's?
 
>>> real 32 bit registers, etc. It is indeed a 32 bit processor. The only
>>> 'problem' is that the address bus of the thing can only use 24 bits to
>>> address memory, and hence you're limited to 16mb of ram on a 68k.
>>  
>> The 68000 was a 16/32 bit chip, because the size of the external data
>> bus was 16 bits, not 24 bits.  The 8088 is considered an 8/16 bit chip,
>> even thouhg its address bus was 20 bits.
> 
> These are implementation issues.
 
Very true -- all this talk about bus/register/etc width are indeed
implementation issues.  If we disregard all implementation issues,
only abstract data types will remain....
 
> By this rationale the 65816 in the IIgs
> is an 8/16 bit chip with a 16/24 bit address bus. 
> 
> These details matter little, IMHO
 
Not quite, or else we'd still all be happy using our 8/8/16-bit 6502,
since bus/etc widths would be "implementation issues which matter
little"...
 
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