Byte conversion

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Hi,

Sorry, me again!

Can anyone explain why some text books use 1,024 and some 1,048 (and the odd doing both) for byte conversion?

Should I come across a question that involves this, don't know what to use.

Many thx,

Rosie

 

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Hmm:hhhmmm Still no answer to this question, then again it is a Bank Holiday

Rosie have you seen this website about Bits/bytes and conversions?

Conversion Calculator

 

Is it because of the northbridge chip, I will have to dig out my old notes but I am sure there's a section in the MM book that refers to 1,048 due to the number of wires and the address bus that allows the northbidge chip to communicate with 8088 cpu.

Wait - yes here we are on page 65 of the Mike Meyers book A+ all in one.

 

Hi,

Haven't seen this. It gets better! Perhaps the 1,024 is easier to remember. Think I'll stick some sunglasses on and go in the garden!

Big thank you.

Rgds

Rosie

 

Hey - now that's a good idea i think I'll join you there with a nice cool beer from the tap

 

Not too many now - you'll be getting your OSes muddled!

Enjoy your beer.

Rgds

Rosie

 

Huh? what are you converting? And 1048 isn't any conversion factor I have ever seen!

Harry.

 

Hi,

Sorry, just picked up on your message. Thks. I have read this, but an earlier book I read referred to the use of 1,024 being correct usage (think I could find it when I need to refer back to it!). Unless I'm mistaken the earlier book is converting a kilobyte as 1,024 bytes, megabyte as 1,024 kilobytes, a gigabyte as 1,024 megabytes and so forth instead of using the 1,048 and continuing up the scale in bytes only each time.

Trying to ascertain if there is a wrong or a right.

Not very well explained. Apologies.

Rgds

Rosie

 

Hi Harry,

It's memory addressing. (See my message just previous to ucheekymoney).

Many thxs and rgds

Rosie

 

Er - the use of 1024 is that it is a power of 2 - and memory is very much a binary thing.

Where did the value of 1048 come from?

Harry.

 

Hi,

I hope the following is allowed as it isn't word for word:

If you have access to MM's All-in-One on memory, it refers to the original address bus (20 wires) - 2 to the power of 20 = 1,048,576 or 1 MB.

1 KB = 1,024 bytes, 1 MB = 1,048 bytes, 1 GB = 1073 bytes. It always seems to show conversion in 'bytes' . In an earlier book I read it referred to 1,024 bytes in 1 KB, 1,024 KB = 1 MB, 1,024 MB = 1 GB and so forth. There was mention somewhere within of 1,048 conversion being incorrect use.

Rgds

Rosie

 

Hi Rosie , if you are refering to the chapter on microprocessors then i think you are misinterpereting the conversions.
1KB = 1,024 bytes
1MB = 1,048,576 bytes or 1,048 KB
1GB = 1,073,741,824 bytes or 1,073,741 KB or 1,073 MB
when you say you are getting 1,024 and 1,048 values they are not for the same range ( one being for KB and one for MB)
Hope this is of some help to you Gary

 

This is muddling things somewhat! You are confusing binary prefixes with decimal prefixes. See here for a good article on the subject.
Using the IEC prefixes the above should be witten:
1KiB = 1,024 bytes
1MiB = 1,048,576 bytes or 1,048 KB (= 1024KiB)
1GiB = 1,073,741,824 bytes or 1,073,741 KB or 1,073 MB (=1024 MiB)

The problem is that the IEC prefixes have never really caught on, so the confusion continues.

Harry.

 

I have the book - but it is at home. I'll dig it out tonight and comment further.

Harry.

 

Hi Gary,

Thx very much for the response. Yes, it looks like the right chapter. I do see how the figures have been achieved in both, but I'm puzzled as to why one is considered incorrect to use. Why are the books taking different routes? It looks like Harry may have picked up on this.

Rgds

Rosie

 

Hi Harry,

Thx for the responses and the link. Yes, I've come across something similar a few days ago. If you get the chance to pick up the book, I'd be grateful for your comments.

Big thank you,

Rosie

 

OK - I've now dug out my copy and I assume you are refering to page 66.

First - you are truncating the values given there - the value he gives for 1MB is 1,048,576 bytes. Which is why I was confused by your 1,048 figure - you had left out the next 3 digits!

Note that he doesn't use the CIE prefixes (almost nobody does).

Harry.

 

Hi Harry,

Thank you for taking the trouble of looking up the info. It is not the calculations I question (I typed this in a hurried, truncated fashion as I'm nose in book trying to pack in my revision, and assumed that some will be familiar with the these figures).

It hadn't come to the fore until I read MM's book. I wondered why conversion using 1,048,576 was considered wrong by the writer and the use of 1,024 in each case (bytes to kilobytes to megabytes etc) was considered correct.

Terribly confusing. Either way, I'll work from MM's book as it's widely used and hope for the best.

Thx again. Much appreciated.

Rgds

Rosie

 

Er - where does he say this is 'wrong'?

That part, starting on the previous page in my edition, gives conversion factors, and points out (for memory) that the multiples are powers of 2, not powers of 10.

Harry.

 

This comment is not taken from MM's book, but from text I read a year ago (my post message no. 8 on page 1 refers). I only queried this on reading MM's book subsequently. I'll see if I can hunt out the earlier book in question to recollect the reasoning behind this.

Rgds and thx

Rosie