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'[PIC] High Nibble'
2008\12\20@003158 by solarwind

picon face
When you do

movlw     0x0F

W looks like this: 000 1111

What is called the "high" nibble? The "0" 4 bits or the "1" 4 bits?

--
solarwind

2008\12\20@005627 by Rolf

face picon face
solarwind wrote:
> When you do
>
> movlw     0x0F
>
> W looks like this: 000 1111
>
> What is called the "high" nibble? The "0" 4 bits or the "1" 4 bits?
>
>  
The 0000 bits are high, the 1111 bits are the low ones, and it's
traditionally called a nybble to match byte, but I see wikipedia says
nybble is just an alternate....

Rolf

2008\12\20@005732 by Harold Hallikainen

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flavicon
face

> When you do
>
> movlw     0x0F
>
> W looks like this: 000 1111
>
> What is called the "high" nibble? The "0" 4 bits or the "1" 4 bits?
>
> --
> solarwind

The high nibble (or half byte) is the high or most significant half. In
the case of 0x0f, the 0 is in the high half, and the f is in the low half.

Harold

--
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opportunities available!

2008\12\20@011003 by Steve Smith

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Now Sun winder.... this is verbose so that with a little bit of effort you
can learn something....

Bit                        =
1        
Nibble                =
1111        
Byte                        =
1111 1111        
Word                        =                                          1111 1111
1111 1111
Long Word                =                1111 1111 1111 1111 1111 1111 1111
1111

In hex                =                F    F    F    F    F    F    F    F
In Dec                =                                                 4095        255
15   -0
                                       And so on                  65535
So the high order nibble or most significant bits are these ^^^^ if you are
referring to a Byte.

But with larger numbers you need first to be aware if the number you are
dealing with is Big Endean or Little Endean .... That is the order of the
bytes in a word or where the high order bits are. All the above are Big
Endean with the most significant bit on the Left hand side.....

And of course all the above 1's could also be 0's

By the way unless you are using a very odd processor with seven bits
W should contain b'00001111' or .15

Regards
Steve

-----Original Message-----
From: spam_OUTpiclist-bouncesTakeThisOuTspammit.edu [.....piclist-bouncesKILLspamspam@spam@mit.edu] On Behalf Of
solarwind
Sent: 20 December 2008 05:32
To: Microcontroller discussion list - Public.
Subject: [PIC] High Nibble

When you do

movlw     0x0F

W looks like this: 000 1111

What is called the "high" nibble? The "0" 4 bits or the "1" 4 bits?

--
solarwind

2008\12\20@011107 by solarwind

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Thanks, I think I know why my LCD wasnt working now...

2008\12\20@011502 by Matthew Miller

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On Sat, Dec 20, 2008 at 12:31:56AM -0500, solarwind wrote:
> When you do
>
> movlw     0x0F
>
> W looks like this: 000 1111
>
> What is called the "high" nibble? The "0" 4 bits or the "1" 4 bits?

Hi Solarwind,

When writing out binary digits the least significant bit (LSB) is usually on
the far right. Likewise, the most significant bit (MSB) is on the far
left. For this case, the high nibble of a byte would be the four left-most
bits.

You might also want to read about endianess. See:
http://en.wikipedia.org/wiki/Endian

Matthew

2008\12\20@012942 by solarwind

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Thanks, all of you, very useful information.

2008\12\20@045546 by David Meiklejohn

face
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Rolf wrote:
> it's
> traditionally called a nybble to match byte, but I see wikipedia says
> nybble is just an alternate....


Hey, I'm with you - in my PIC tutorials, I spell it nybble, because that's
what I learned.  To me, it's more consistent with byte.  Not that it
particularly matters!


David Meiklejohn
http://www.gooligum.com.au


2008\12\20@092236 by olin piclist

face picon face
solarwind wrote:
> W looks like this: 000 1111
>
> What is called the "high" nibble? The "0" 4 bits or the "1" 4 bits?

This is getting rediculous.

Search for things like "byte order", "bit order", "little endian", and "big
endian", and report back with the answer.  For extra credit discuss "high"
and "low" as it applies to bytes within a multi-byte word.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2008\12\21@024303 by Sean Breheny

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Hi Olin,

On Sat, Dec 20, 2008 at 9:22 AM, Olin Lathrop <olin_piclistspamKILLspamembedinc.com> wrote:
> This is getting rediculous.
>

Ok, this is a bit mean on my part but I think you need to take some of
your own advice here.

Do you spell check your emails? I often notice spelling errors in your
emails. It is ridiculous not rediculous. This is because it means
"laughable", coming from the Latin word ridere (to laugh) or even more
directly, from the Latin adjective ridiculus (laughable).

Sean

2008\12\21@034953 by solarwind

picon face
On Sun, Dec 21, 2008 at 1:04 AM, Sean Breheny <.....shb7KILLspamspam.....cornell.edu> wrote:
> Hi Olin,
>
> On Sat, Dec 20, 2008 at 9:22 AM, Olin Lathrop <EraseMEolin_piclistspam_OUTspamTakeThisOuTembedinc.com> wrote:
>> This is getting rediculous.
>>
>
> Ok, this is a bit mean on my part but I think you need to take some of
> your own advice here.
>
> Do you spell check your emails? I often notice spelling errors in your
> emails. It is ridiculous not rediculous. This is because it means
> "laughable", coming from the Latin word ridere (to laugh) or even more
> directly, from the Latin adjective ridiculus (laughable).
>
> Sean

I would have made several such comments like that about many people on
the list by now, but unlike them, I realize the purpose of this list
and why we are here. It's best to just gain knowledge and filter out
the crap that people come with.


--
solarwind

2008\12\21@082536 by Gerhard Fiedler

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On 2008-12-20 06:09:37, Steve Smith wrote:

> Word = 1111 1111 1111 1111

Actually, while the sizes of "bit" and "byte" are rather universal (1
and 8 bits), the size of "word" isn't.

"Word" is usually used in some context that allows one to deduce its
size in bits and usually means something between 8 and 64 bits (though
neither is a hard limit). See also
<http://en.wikipedia.org/wiki/Word_(computing)>.

Gerhard

2008\12\21@084508 by Jan-Erik Soderholm

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Gerhard Fiedler wrote:
> On 2008-12-20 06:09:37, Steve Smith wrote:
>
>> Word = 1111 1111 1111 1111
>
> Actually, while the sizes of "bit" and "byte" are rather universal (1
> and 8 bits), the size of "word" isn't.

The term "word" is often hard linked to whatever architecture
one is speaking about. Could be 12, 14, 16 or 32 bits (for PICs),
36 bits (DEC PDP10), 128 bits (Intel Itanium) or any other
size, more or less.

>
> "Word" is usually used in some context that allows one to deduce its
> size in bits and usually means something between 8 and 64 bits (though
> neither is a hard limit). See also
> <http://en.wikipedia.org/wiki/Word_(computing)>.
>
> Gerhard

2008\12\21@095021 by olin piclist

face picon face
Sean Breheny wrote:
> Do you spell check your emails? I often notice spelling errors in your
> emails. It is ridiculous not rediculous.

I don't spell check, and often type quickly.  Usually I give a quick
proofread but sometimes don't catch things.  Then there are the true
spelling errors where I wouldn't know without looking it up, like in this
case.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2008\12\21@100432 by olin piclist

face picon face
Gerhard Fiedler wrote:
> Actually, while the sizes of "bit" and "byte" are rather universal (1
> and 8 bits),

I agree that nowadays "byte" means 8 bits.

I just want to point out this was not always so.  A notable exception was
the CDC 6600 and its decendents.  That used a 48 bit word of 6-bit bytes.

Then there is MPLINK that reports the size of each 14 bit word as two bytes.

Since byte didn't universally mean 8 bits, the internet standards refer to
"octets" to avoid confusion.

> the size of "word" isn't.

Yes, I think of "word" as being context-dependent.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

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