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Sunday, October 23, 2011

How Much Data Is That!?

Whenever we discuss quantities of data, we tend to do it in the abstract. We speak of a kilobyte, or a megabyte or a gigabyte without really knowing what it represents.

The following table shows various quantities of bytes, in each power of ten. Usually, they are shown with multiples of 2 and 5 also. For example, 1 Kilobyte, 2 Kilobytes, 5 Kilobytes.

All the examples are approximate and are rounded. For example, a computer card has 80 columns. If 50 columns contain data on a card, then two cards will be 100 bytes. Also, a 3-1/2 inch diskette can contain 1.4 Megabytes. Showing it as 1 Megabyte reflects both (a) the diskette not typically being filled and (b) rounding. Finally, a CD-ROM can hold more than 500 Megabytes. However, it is listed at that level as "typical" and as the closest match.

Bytes (8 bits)

0.1 bytes: A single yes/no decision (actually 0.125 bytes, but I rounded)
1 byte: One character
2 bytes:
5 bytes
10 bytes: One word (a word of language, not a computer word)
20 bytes:
50 bytes:
100 bytes: Telegram; two punched computer (Hollerith) cards
200 bytes:
500 bytes:

Kilobyte
1,024 bytes; 210;
approx. 1,000 or 10 3

1 Kilobyte: Joke; (very) short story
2 Kilobytes: Typewritten page
10 Kilobytes: Page out of an encyclopedia
20 Kilobytes:
50 Kilobytes: Image of a document page, compressed
100 Kilobytes: Photograph, low-resolution
200 Kilobytes: Two boxes (4000) punched computer (Hollerith) cards
500 Kilobytes: Five boxes, one case (10,000 of punched computer (Hollerith) cards

Megabyte
1,048,576 bytes; 220;
approx 1,000,000 or 10 6

1 Megabyte: Small novel; 3-1/2 inch diskette
2 Megabytes: Photograph, high resolution
5 Megabytes: Complete works of Shakespeare; 30 seconds of broadcast-quality video
10 Megabytes: Minute of high-fidelity sound; digital chest X-ray; Box of 3-1/2 inch diskettes
20 Megabytes: Two boxes of 3-1/2 inch diskettes
50 Megabytes: Digital mammogram
100 Megabytes: Yard of books on a shelf; two encyclopedia volumes
200 Megabytes: Reel of 9-track tape; IBM 3480 cartridge tape
500 Megabytes: CD-ROM

Gigabyte
1,073,741,824 bytes; 230;
approx 1,000,000,000 or 10 9

1 Gigabyte: Paper in the bed of a pickup; symphony in high-fidelity sound; broadcast quality movie
2 Gigabytes: 20 yards of books on a shelf
5 Gigabytes: 8mm Exabyte tale
10 Gigabytes:
20 Gigabytes: Audio collection of the works of Beethoven; five Exabyte tapes; VHS tape used to store digital data
50 Gigabytes: Library floor of books on shelves
100 Gigabytes: Library floor of academic journals on shelves; large ID-1 digital tape
200 Gigabytes: 50 Exabyte tapes

Terabyte
1,099,511,627,776 or 240;
approx. 1,000,000,000,000 or 10 12

1 Terabyte: Automated tape robot; all the X-ray films in a large technological hospital; 50,000 trees made into paper and printed; daily rate of EOS (Earth Orbiting System) data (1998)
2 Terabytes: Academic research ligrary
10 Terabytes: Printed collection of the U. S. Library of Congress
50 Terabytes: Contents of a large mass storage system

Petabyte
1,125,899,906,842,624 bytes or 250
approx. 1,000,000,000,000,000 or 10 15

1 Petabyte: 3 years of EOS data (2001)
2 Petabytes: All U. S. academic research libraries
20 Petabytes: 1995 production of hard-disk drives
200 Petabytes: All printed material; 1995 production of digital magnetic tape

Exabyte
1,152,921,504,606,846,976 bytes or 260
approx. 1,000,000,000,000,000,000 or 10 18

5 Exabytes: All words ever spoken by human beings.

Zettabyte
1,180,591,620,717,411,303,424 bytes or 270
approx. 1,000,000,000,000,000,000,000 or 10 21

Yottabyte
1,208,925,819,614,629,174,706,176 bytes or 280
approx. 1,000,000,000,000,000,000,000,000 or 10 24

(Via James S. Huggins' Refrigerator Door )
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