x

I just wondered what '64 bit' meant. This is what Wiki told me. It's
meaningless. Don't they have anyone that can explain things in plain
English? At school I was top of the class at comprehension. But this means
nothing to me.

In computer architecture /wiki/Computer_architecture, 64-bit integers
/wiki/Integer_(computer_science), memory addresses /wiki/Memory_address,
or other data /wiki/Data units are those that are at most 64 bits
/wiki/Bit (8 octets /wiki/Octet_(computing)) wide. Also, 64-bit CPU
/wiki/Central_processing_unit and ALU /wiki/Arithmetic_logic_unit
architectures /wiki/Computer_architecture are those that are based on
registers /wiki/Processor_register, address buses /wiki/Address_bus, or
data buses /wiki/Bus_(computing) of that size. 64-bit is also a term given
to a generation of computers in which 64-bit processors were the norm.
64-bit CPUs have existed in supercomputers /wiki/Supercomputers since the
1960s and in RISC /wiki/RISC-based workstations
/wiki/Computer_workstation and servers /wiki/Server_(computing) since
the early 1990s. In 2003 they were introduced to the (previously 32-bit
/wiki/32-bit) mainstream personal computer /wiki/Personal_computer
arena, in the form of the x86-64 /wiki/X86-64 and 64-bit PowerPC
/wiki/PowerPC processor architectures.
Without further qualification, a 64-bit computer architecture generally has
integer and addressing registers /wiki/Processor_register that are 64 bits
wide, allowing direct support for 64-bit data types and addresses. However,
a CPU might have external data buses /wiki/Data_bus or address buses
/wiki/Address_bus with different sizes than the registers, even larger
(the 32-bit Pentium /wiki/Pentium had a 64-bit data bus, for instance).
The term may also refer to the size of low-level data types, such as 64-bit
floating-point /wiki/Floating_point numbers.

And why is this message called 'x'? Because this newsreader insists that
every message has a title. Why?

Bill

"Bill" wrote in message
...
I just wondered what '64 bit' meant. This is what Wiki told me. It's
meaningless. Don't they have anyone that can explain things in plain
English? At school I was top of the class at comprehension. But this means
nothing to me.

The answer to the simple question you posed is also simple.

In computing, which uses binary arithmetic, each binary digit (with a value
of either 1 or 0) is commonly referred to as a 'bit'.

So 64 bit means something constructed of 64 binary digits (or whatever the
correct term is).

Beyond that it gets a little more complicated.......

Bill wrote:
I just wondered what '64 bit' meant. This is what Wiki told me. It's
meaningless. Don't they have anyone that can explain things in plain
English? At school I was top of the class at comprehension. But this means
nothing to me.

You mean "Wikipedia" - there are other wikis.

You could try http://simple.wikipedia.org/ - but I don't think they have
an article on 64-bit.

In an earlier contribution to this discussion,
David WE Roberts wrote:

"Bill" wrote in message
...
I just wondered what '64 bit' meant. This is what Wiki told me. It's
meaningless. Don't they have anyone that can explain things in plain
English? At school I was top of the class at comprehension. But this
means nothing to me.

The answer to the simple question you posed is also simple.

In computing, which uses binary arithmetic, each binary digit (with a
value of either 1 or 0) is commonly referred to as a 'bit'.

So 64 bit means something constructed of 64 binary digits (or
whatever the correct term is).

Beyond that it gets a little more complicated.......

So each 64-bit 'word' can have any one of 2^64 (2 to the power of 64)
possible values - which is about 18 million million million in real money.

If you like, you can say that data are moved around in 64-bit chunks, and
that each data item has a precision of 1 in 18 million million million.

As others have said, it's slightly more complex than that because computer
memory can be used in different ways for handling text and real
(non-integer) numbers, etc. But hopefully, you will get the general idea
from this.

--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Bill wrote:

I just wondered what '64 bit' meant. This is what Wiki told me. It's
meaningless. Don't they have anyone that can explain things in plain
English? At school I was top of the class at comprehension. But this means
nothing to me.

In what context Bill?

DSP's (meters), computing general, processors...? Means slightly different
things in all those catagories!

Generally, it usually refers to the internal architecture of a digital
device and how "big" the largest possible number carried in a "word" of
data can be,

For example, 8 bit "blocks (words)" can hold a number no greater than 255
16 bit blocks can hold a number up to 65525
etc etc.

In DSP's and non integer based applications, it can mean considerably higher
precision numbers can be used (more numbers after the decimal point).

On a consumer level, it's not usually anything to worry about but something
the marketing dept love to put on the front of a device in big letters
because it sounds technical and impressive...

Basically, if you need a 64bit architecture (or indeed if you have one!)
you'll know about it otherwise it's not really too much to worry about.

As for subject lines in newsgroups... It's to help us fallable humans pick
up stuff that we're interested in and follow the thread... or not

Cheers,
Mike

Bill wrote:

I just wondered what '64 bit' meant. This is what Wiki told me. It's

Its a very general question, for which any comprehensive answer would be
very broad. Rather like "What does 1600cc mean?"

If you narrowed it down a bit to say "what is a 64 bit processor" then
it gets easier to answer if you don't mind their being a list of caveats
and exceptions to every statement! ;-)

But I couldn't frame that question because I honestly had never heard of a
64 bit processor.

And why is this message called 'x'? Because this newsreader insists that
every message has a title. Why?

To encourage folks to give nice meaningful names to their messages -
make the group easier to follow and all that.

But software shouldn't be used to blindly enforce something that is protocol
or manners, right as it might be. It's officiousness.

Bill

"Bill" wrote in message
...
I just wondered what '64 bit' meant. This is what Wiki told me. It's
meaningless. Don't they have anyone that can explain things in plain
English? At school I was top of the class at comprehension. But this means
nothing to me.

The answer to the simple question you posed is also simple.

In computing, which uses binary arithmetic, each binary digit (with a value
of either 1 or 0) is commonly referred to as a 'bit'.

So 64 bit means something constructed of 64 binary digits (or whatever the
correct term is).

Beyond that it gets a little more complicated.......



Yes, but that's a good start. Far better than Wiki's attempt.

Bill

So each 64-bit 'word' can have any one of 2^64 (2 to the power of 64)
possible values - which is about 18 million million million in real money.

If you like, you can say that data are moved around in 64-bit chunks, and
that each data item has a precision of 1 in 18 million million million.

As others have said, it's slightly more complex than that because computer
memory can be used in different ways for handling text and real
(non-integer) numbers, etc. But hopefully, you will get the general idea
from this.

Yes indeed I do. Thank you.

Bill

On 26/11/09 19:26, Bill wrote:

I honestly had never heard of a 64 bit processor.

But were you aware of 8 bit (around the BBC micro/ZX Spectrum era), 16
bit (PCs around the DOS era) or 32 bit (PCs from the Windows 3.x era)
processors?

It's not simply down to the size of numbers that a machine can handle,
after all 8 bit machines could handle numbers larger than 256, and 16
bit could handle numbers bigger than 65535.

The main driver for increasing bit depth is to address larger amounts of
memory, for most home users the roughly 4GB limit hasn't hit yet, but
for businesses, servers capable of handling 32GB or 256GB of memory are
not uncommon.

Similarly there are several instances related to disk storage where the
limit of 2 terabytes rear their ugly head.

"Andy Burns" wrote in message
o.uk...
On 26/11/09 19:26, Bill wrote:

I honestly had never heard of a 64 bit processor.

But were you aware of 8 bit (around the BBC micro/ZX Spectrum era), 16 bit
(PCs around the DOS era) or 32 bit (PCs from the Windows 3.x era)
processors?

It's not simply down to the size of numbers that a machine can handle,
after all 8 bit machines could handle numbers larger than 256, and 16 bit
could handle numbers bigger than 65535.

Specifically it's the size of the 'machine word' - the largest amount of
data that the CPU (Central Processing Unit) can handle in one go. Larger
numbers are handled with 'multiple precision' algorithms - like 'carrying'
and 'borrowing' to add and subtract decimal numbers more than 9.

The main driver for increasing bit depth is to address larger amounts of
memory, for most home users the roughly 4GB limit hasn't hit yet, but for
businesses, servers capable of handling 32GB or 256GB of memory are not
uncommon.

There's no necessary connection between the word size and the 'address
space' - the numbers of words (or bytes) that the processor can access -
4-bit processors used to have 12-bit addresses, and 8-bit processors have
16-bit addresses. The 16-bit Intel processors had a peculiar 'segmented'
addressing scheme.

I suppose I've lost Bill by now, unless he was having us on about his
inability to understand this sort of stuff.

(Actually he looked at the wrong Wiki page -
http://en.wikipedia.org/wiki/Machine_word would have been better - though
it's not obvious that is what is meant when people talk about a 64-bit
processor.)

--
Max Demian