jameshanley39@yahoo.co.uk wrote
> Rod Speed <rod.speed....@gmail.com> wrote
>> jameshanle...@yahoo.co.uk wrote
>>> Jethro <Wil...@somewhere.org> wrote

>>>> I notice there is always a great disparity between stated hard
>>>> drive capacity and actual usable capacity after formatting.

>>>> Is there a chart or other paper anywhere showing maybe comparisons
>>>> of this between drives, and maybe an explanation of why and how it happens?

>>> the relationship between a megabyte( 2^20) and an approximation
>>> of the megabyte, (10^6), is a factor of 1.048576.

>>> Meaning that to get from one to the other, you multiply or divide by 1.048576

>>> A megabyte is 1,048,576 bytes. The Approximation is 1,000,000.
>>> Somtimes one is called the binary megabyte and the other
>>> the decimal megabyte, but it's not a different number system.

>> It is actually, different base.

>>> The approximation or decimal megabyte is just using 10^ instead of 2^.

>> So its a different number system.

> No,

Fraid so.

> 2^x cannot even be binary. The number 2 doesn't even exist in binary.

Utterly mangled and completely irrelevant to which base is used.

> Perhaps the term base has 2 meanings.
> Base^Exponent, and base as in number system.

http://en.wikipedia.org/wiki/Number_system

> But Binary - as far as I know - only applies to number systems, and
> that is the term I use here. It is in that context that I use the word base.

And you can have any base you like in that context.

>>> The 10^6 figure is a smaller unit.. So more of it are used to equal a
>>> corresponding amount of the the 'binary megabyte', which is a larger unit.
>>> "they say" that Hard Drive marketting people use the 'decimal
>>> megabyte' because it sounds better, larger numbers.

>> Only the pig ignorant fools. Its the SI standard, legally required in many countrys.

> Were they to not use the SI standard, and to use [what you deny to be]
> the standard meaning in computing,

The binary form is nothing like the standard meaning in computing.
The decimal form is mostly whats used in computing, most
obviously with cpu speeds, comms speeds, etc etc etc .

Its only MEMORY that has an intrinsically binary organisation
where the binary form is in fact commonly used.

> then I am not convinced that they'd be sued for
> understating the specification of their product.

More fool you.

>> Its the binary gigabyte that makes no sense with something
>> like a hard drive which isnt intrinsically binary organised.

>> And the 1.44MB floppy is actually a weird binary/decimal hybrid.

> I haven't read about how they organise their data, but electronics knows HIGHS
> and LOWS, ACTIVE or Not. At the lowest level, it appears to me to be binary.

The lowest level is completely irrelevant. Clearly cpu speeds have never
been stated using binary multipliers, even tho they are certainly digital devices.