32 or 16 bits?
COTTRELL, JAMES
cottrell at nbs-vms.arpa
Tue Jan 14 06:10:03 AEST 1986
/*
> It seems to me that the arguments around 16-bit vs. 32-bit
> architectures have gotten a little out-of-hand.
Most assuredly.
> There are two DIFFERENT standards by which to judge processors.
At least.
> First, the width
> of the physical data bus. By this standard, the 8088 is an 8-bit
> processor, 8086 and 68000 16-bits, and the 68020 32-bits.
Many people (including me) disdain this standard. However, it is
easy to measure and the results (by this standard) are nondebatable.
> The second standard is the internal organization of the processor.
>My own definition for this standard is the ability of the processor to
>execute ALL of its data move, logical, and arithmetic instructions on
>a given word size. ( Note. I emphasize that this is MY standard. )
>By this criterion, the Intel products up to and including the 80286 are ALL
>16-bit processors, as are the 68000 and 68010. (They come REAL close to 32,
>but fall down on the MUL instructions). The 68020 is a real 32-bitter in both
>cases.
I think you are being a little hard. Consider that the 8-bit micros have
NO multiply or divide at all (except the 6809 which has 8 bit multiply
only). By your definition they are zero bit machines. Or maybe if it had
NO multiply at all it would qualify as a 32 bit machine. Consider further
that multiply & divide are the only primitive operations that return
a different number of bits than they consume (anticipating the counter-
example of `convert short to long' etc., I dismiss it with a wave of the
hand). Consider lastly what percentage of instruxions are axually
multiply & divide. I think the 680[01]0 come close enuf to be called 32 bit.
And the 6800 is a 16 bit. But then, that's just *my* opinion.
> The point of all this is that there are several ways of looking at the
>issue, any given one of which is correct, depending on what you're looking
>for. I don't mind hearing discussions, even religious ones, but die-hard
>dogmatism is never comfortable for those on the outside.
What is religion besides diehard dogmatism?
jim cottrell at nbs
*/
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