Have you ever really thought about digital storage capacity? As a result of the following experience I did.

Last year I have re-read a book as an e-book on my PDA that I quite some years earlier had bought and read in paper form. It's a trilogy of about 500 pages in conventional book format. It was the longest single text I had read off screen of any kind so far and I found it quite convenient in use. I used a Pocket PC with a 4 inch VGA screen. The 640x480 resolution on a screen of such size gives a very high resolution that offers an exceptionally sharp image which makes the letters indistinguishable from printed text and it is in no way distracting from the reading process. I have used both 'flipping' to the next page and 'auto scroll', which makes the text move smoothly from bottom to top at an adjustable speed, as the two main methods to advance through the text. The screen is lit and you can adjust it to your preferred level. You can read in the brightest sunshine and in the complete dark. The font and size of the characters can be adjusted to your preference. The text can be read in 'portrait' and in 'landscape' orientation. I prefer landscape on a device of this size. I have read several more e-books this way since and all in all I have no problems with reading books this way compared to reading them 'the old way'.

But because of this experience using these e-book files I started to think about the differences in storage size and physical size between the old paper book and the modern variety.

If you think about it and do some calculations the relative size of this thing and its storage capacity make you become aware of how staggering the developments on the storage front have been over the past few decades. Take the SD (Secure Digital) storage card for instance. At 32x24x2.2 mm it is about the size of a postage stamp and has a volume of 1613 cubic mm or 1.6 ml. The one I used in this device has a storage capacity of 4 Gigabyte. That's 4,000,000,000 bytes. The trilogy I mentioned is in simple .TXT files and in total is about 1 Megabyte in size. Which means this memory card can hold 4000 of these 500 page books. That's 2 million pages. But let's not forget about data compression. Text files can be compressed very well. I compressed these with WinRAR and it was reduced to a nice round 25%. So with compression 8 million pages can be stored on this card. How much is 8 million pages exactly?

Well the book in paper form is a standard paperback sized book and it is 3 cm thick. With compression 16000 of these books can be stored on this 'postage stamp on steroids'. That's a stack of books 480 meters high or the same in bookshelf space. That's a reasonably sized bookshop I think. How many of us will read 16000 books in their lifetime?

The exact sizes of this particular book are 20x12.5x3 cm. That's a volume of 750 cubic centimeters or 0.75 liter. Times 16000 books is 12000 liters or 12 cubic meters of books. Not bad for a gizmo of 1.6 ml in size. It's 7.5 million times as efficient in terms of storage space volume compared to regular paper books.

There are already Mini-SD cards (20x21.5x1.4 mm - 602 cubic mm or 0.6 ml) and Micro-SD cards (11x15x1mm - 165 cubic mm or 0.165 ml) of 2 GB capacity. Six Micro-SD cards take up less than one ml of space. With almost a tenth the size of a regular SD-card they currently hold 5 times as much data per volume. That's 36 million times as efficient compared to paper books.

That's impressive to say the least and the end of these developments is not in sight at all.

The PDA I read the book on (HP hx4700) has a volume of 150 ml and a weight of 190 grams.
The book I already mentioned is 750 ml, five times bigger, and weighs 580 grams. That's three times as heavy. The Pocket PC fits easily in most pockets (hence the name) while a standard paperback book cannot be made to disappear on your person quite as easily.

What do these simple hard figures tell us about the future of books? Bought any vinyl LP's lately? When did you shoot your last film roll?

I don't think digital books will take over quite as quickly as digital cameras have. But I could be wrong.

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I made these calculations about a year ago I think. Things have changed since. Now there are 4Gb micro SD cards. So the last figure can now be doubled to 72 million times as efficient as paper.

Now you see how BIG these little memory cards actually are?