Alessio Palma wrote:
>
> Before all I apologize for my english.
>
> Garry Hamilton ha scritto:
>
> > You know, I was going to stay out of this one ...
> >
> > It is true that one (1) bit is the smallest
> > discreet unit of data.
> >
> > Also that 4 bits are a Nibble,
> > also that 8 bits are a Byte.
> >
> > These are truths on every processor I've worked
> > on. (Some bus circuitry requires a ninth parity
> > bit, but that's not part of the data.)
>
> That's not correct, from my view point of course, parity bit is part of
> the data, in fact we use it to know if data itselft is corrupt.
>
The above IS correct. Unless one is talking about data being
passed through a network (packets), etc. The Parity Bit is
in an internal thing used by the PC only to ensure that the
data is not corrupt from either a bad memory chip or the RAM
refresh rate being set too low.
> > When we get to the WORD, things begin to get
> > a little fuzzy. On some processors, a BYTE and
> > a WORD are the same.
>
> Mmmm I think that a byte is defined as 8 bit, a word as 16 bits and so...
>
A Byte and a Word are not the same thing.
> > On contemporary Intel processors, a WORD is 2
> > BYTES. On higher end CPUs a WORD can be 32 or
> > even 64 bits. It depends on the CPUs "natural"
> > data unit size, based on its register width.
>
> I can't share your point of view, a WORD is defined as 16 bits, then 32
> bit is not a word. CPU natural data unit size is different topic. Each
> processor can manage data of different size, anyway on a C-compiler in
> which we have 16 bits char types don't means byte=16 bits, it means that
> on this compiler the char type (not byte) is 16 bits long.
>
32 bits is a Double Word and 64 bits is a Quad Word.
> > Having said all that, I still teach my students
> > that:
> > 1 = BIT
> > 4 = NIBBLE
> > 8 = BYTE
> > 16 = WORD
> > 32 = DOUBLE WORD
> > 64 = QUAD WORD
>
> I disagree : ( ---> (but I always add the "CPU-dependent" disclaimer).
>
And this is the correct thing to teach your students.
And for what it is worth, I program in assembly language.
And without a clear understanding of Bit, Nibble, Byte, etc.
you're dead in the water without a paddle. :-)
> > With a little more personal restraint I might have
> > stayed out of this one, but THE VOICES MADE ME!
> >
> > Trust The Source,
> > Garry
> > ---------------------
> > >
> > > Really?!? What are Word and DWord ?
> > >
> > > I know that:
> > > 4 bits are called NIBBLE
> > > 8 bits are called BYTE
> > > 16 " " " WORD
> > > 32 " " " DOUBLE WORD
> > >
> > > 1 bit is the unit of information and not byte.
> > >
>
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