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Thread ID: 21870 2002-07-06 01:39:00 XP & Hard Disc Size TABRJ (888) Press F1
Post ID Timestamp Content User
60223 2002-07-06 01:39:00 I have just purchased a new computer with XP Home Edition. It was sold to me as having a 40.oGB hard drive. When I go START my COMPUTER and click on C: properties is says 32.6 Gb D: 4.6Gb giving a total of 37.2Gb. Q. Does XP take up the other 2.8Gb or is it a 37.2Gb hard drive? TABRJ (888)
60224 2002-07-06 01:54:00 Hi Tabjr,

Most manufacturers sell harddrives as being e.g. 40GB but are actually 40,000,000,000 bytes when a 'real' 40GB would be 42,949,672,960 bytes.

So therefore taking your 40GB drive and dividing by a 'real' GB would come to 37,252,902,985 bytes or approximately 37.25GB.

Confused so are a lot of us!!

Cheers, Babe.
Babe Ruth (416)
60225 2002-07-06 02:27:00 I've long forgotten the mathematical statistics behind disk sizes, but it all started with bits. There are 8 bits to a byte (a bit being a single 0 or 1). 8 bits are used to define 1 character (like an "a").

Trouble is, 8 doesn't divide nicely into 1,000. So 1Kb is actually 1024 bytes. For simplicity rounding takes place.

We meet rounding in other areas. Due to a lack of 1c coins $1.96 is charged at $1.95; A 1116cc engine in a car is refered to as 1100cc. For some reason computers round up.
Heather P (163)
60226 2002-07-06 03:08:00 Thanks to you both. I now understand, well sort of. Many thanks :-) TABRJ (888)
60227 2002-07-06 03:29:00 Not exactly right Heather . It's all about powers of 2 or 10 . 10^3 --> 1000, 2^10 --> 1024 ( 1 k ) . 2^10 x 2^10 = 2^20 ( 1 MB) . 10^3 x 10^3 = 10^6 (1 million) .

A 3 . 5" floppy has 2880 sectors . Each sector is 512 (2^9) bytes -- 1/2 kB .
That makes 1 . 44 MB . How? Why? (Windows will format a floppy and say it has 1 . 36 MB) . The "2880" is a decimal number . The "k" is a binary value .

IBM made the first hard disks . There were about 50 platters, each 24" diameter . They held (I think) 20 MB .

IBM decided at some stage that 1 MB was 1000 (decimal) kB (powers of 2 "k") . That has been the normal unit . MS have recently adopted the ISO standard,

But disk drive manufacturers will use whatever units will give the largest numbers in their advertising . They will often use the IBM unit . They might use the decimal million for even bigger numbers . They have stopped using the "raw" capacity --- unformatted size, because IDE drives are factory formatted . A 1 . 44 MB floppy is 2 MB unformatted: that's how MS can use a 1 . 7 MB format for their distribution disks .

"Lies, damned lies, and advertising . " ]:)
Graham L (2)
60228 2002-07-06 05:17:00 Graham,

Did I mention that I've forgotten the actual maths behind it cause everytime I try to think about it I get a headache?

Essentially it comes down to the fact that we have 10 fingers so use the decimal system . Computers have only 2 states - on and off - so use the binary system .

Rather than explain the maths (which involves power to and square roots - headache forming stuff) the marketing people find the nearest whole number and round up to it .
Heather P (163)
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