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Originally Posted by stumped
same sales trick as hard drives where xxGb is calculated using 1000 in place of 1024, thus you never get what you thought you were paying for
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Likely most of the "missing" space is the operating system (OS). The quoted memory on all phones, tablets and ereaders is the chip capacity before formatting and excluding the OS. The Partition information, Partition and the formatting all use up storage even apart from the OS.
The physical disc makers are not exactly being dishonest. Memory chips are directly addressed and have an exact power of two of storage. A ten bit address is exactly 1024 locations, a count of 0 to 1023. Disk drives have tracks, like cassette tapes. A CD or DVD or BD has actually only a single spiral track like an LP or 45 disk, though start at the inner.
Long ago the HDD had a fixed number of sections or sectors per track. A Floppy had a hole to indicate the first. There might not be an even number of tracks, platters (all the tracks across all the platters at one head position is a cylinder) or sectors per track, so the total is not a power of two. Then also there might be bad sectors or reserved space for them.
Since the linear velocity of the track is highest at the outer edge you can fit more sectors at the same data density. A floppy on the Victor 9000 / ACT Sirius 1 did this in 1981 by varying the rotational speed. CDs, DVD, BD actually gradually slow the rotational speed when streaming audio or video to keep the data density constant. Modern HDDs will vary the data clock to have higher density and thus more sectors as you move from the inner to the outer edge. Real transfer speeds are thus higher at the outer edge.
All this means is that Chips are usually multiples of 1024 and any physical rotating storage medium is an arbitrary number of bytes. RAM doesn't need "partitioned" and "Formatted", persistent storage does, which loses some storage.
Actually 2 G Byte RAM or Flash is really 2 Gibi bytes.
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The Institute of Electrical and Electronics Engineers (IEEE) began to collaborate with the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC) to find acceptable names for binary prefixes. IEC proposed kibi, mebi, gibi and tebi, with the symbols Ki, Mi, Gi and Ti respectively, in 1996.
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https://en.wikipedia.org/wiki/Binary_prefix#gibi
So technically the Drive makers are honest (and in the detail they explain about formatting) and the Chip makers are inaccurate.