# Gigabyte error in DC book

Discussion in 'Feedback and Suggestions' started by Fael, Feb 2, 2011.

1. ### Fael Thread Starter New Member

Feb 2, 2011
2
0
First of all, I would like to thank you very much for offering the vast amounts of electronics knowledge through your books. I am enjoying the DC book thoroughly and am planning to finish reading all the material you have made available.

However, I would like to point out a little mistake you made on page 123 (133 on the pdf file) of the DC book. You wrote:

"Looking at this scale, we can see that 2.5 Gigabytes would mean 2.5 x 10^9 bytes, or 2.5 billion bytes."

I understand that you wanted to explain scientific notation but that asseveration is wrong. Bytes are measured in binary:

8 bits = 1 byte
1024 bytes = 1Kb
1024 Kb = 1Mb
1024Mb = 1Gb

As you may have noticed, 1 x 2^10 = 1024. Therefore, 2.5 Gb are actually 2.5 x 2^10 x 2^10 x 2^10 = 2.5 x 2^30 bytes.

2. ### Wendy Moderator

Mar 24, 2008
21,417
2,948
Uhhh, no. You can measure bytes in whatever number system you are comfortable with.

Since humans use decimal, that is the normal convention.

When I bought my 500Gig hard drive, it was understood it was in decimal. It was also understood this number is heavily rounded off.

There is no rule of thumb, none, that says anything about binary being the default math. How many folks off the street know the difference?

It's like the old joke, there are 10 kinds of people in the world, those who understand binary, and those who don't.

All of these number are decimal. All of them have been used to describe RAM in computers for over 35 years. None use binary, even though the underlying number was derived via binary.

1,024 (2^8) ≈ 1K
65,536 (2^16) ≈ 64K
1,073,741,824 (2^30) ≈ 1 Gig

Welcome to AAC!

Last edited: Feb 2, 2011
3. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
727
Typically, once 1 Megabyte is reached, they use the decimal system. A 2GB Flash card is often 2000 MB, rather than the bits expanded to GB. Hard drives follow that convention as well, typically the total is a few percent less due to bad sector re-allocation.

4. ### Georacer Moderator

Nov 25, 2009
5,177
1,285
I 'll disagree on that. I believe that all the K, M and G letters in informatics refer to the binary system, unlike the K, M and G in physics that refer to the decimal system.

As an EE and computer studies student this has been very strongly cleared to me. This enables the systems to represent their limit addresses easily.

It happens that 2^10 is close to 1000, and that's why it works for non-involved people, but in later powers, like 2^30 the result is much different that 10^9.

As for the commercial products, well, it wouldn't make much sense to say that your HD can hold 288,5GB of information, thus the rounding.

Oh, and Bill, 1024 is 2^10 not 2^8.

5. ### debjit625 Well-Known Member

Apr 17, 2010
790
186
I also disagree on that,the topic on the book was for Metric notation not for binary.

Hard disk manufacturers specify hard disk size in SI units and its known as physical size.

Now on the other hand file system(like FAT,FAT32 or NTFS) of the OS specify 1 byte = 8 bits and so on ,so we called it logical size

And this is why we dont get the full capacity of a HDD as specified by the manufacturers when its running under an OS which shows the logical size as per the file system (one of my old hdd of 160GB gave me just 127GB under NTFS with XP as OS ).

This conflict is caused for the physical construction of HDD,not its a standard way to measure binary quantities.

Their are also some other errors in the book,one of which also I have posted but got 0 reply so I stopped ...will try some other time..

Anyway Fael welcome to AAC.

6. ### Fael Thread Starter New Member

Feb 2, 2011
2
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Thank you all for the welcoming. I am not 100% certain that I am right, but with Georacer and debjit625 agreeing with me on the original issue, it might be interesting to review it.

I am definitely not trying to annoy, impress or affect others in any negative way. I don't want any kind of recognition either. I just thought it would be helpful if I pointed some, in my opinion, mistakes on the ebook.

That is all for now but I expect I will be coming back as I advance through the books. Thank you all!

7. ### Georacer Moderator

Nov 25, 2009
5,177
1,285
The E-Book is under constant review and all pointers on errors are welcome, so debjit625, please keep proofreading. I am sure you other posts were looked at at least.

8. ### tom66 Senior Member

May 9, 2009
2,613
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KiB, MiB, GiB, TiB... = Binary (1024, 1048576, ...)
KB, MB, GB, TB = Decimal (1000, 1000000, ...)

However, operating systems often report space in GiB, but label it as GB, to add to confusion. Things like RAM are often measured in GB, but are almost always binary powers of two (or close multiples, for example 192 MB = 1.5x 128 MB.) 1.44MB floppies are in neither decimal megabytes or binary megabytes (just to be confusing) - they can be 1.41 true MB or 1.47 MiB.

If you are confused, you are not alone.

Apr 17, 2010
790
186
I will....