[extropy-chat] rfid

[Dirk Bruere]

Luke Howison wrote:

>RFID tags hold a string of bits called the EPC (electronic product
>code).  It isn't 95 digits long, it is 96 *BITS* long.  So all your
>calculations were borked, sorry guys.  However, the real story is
>still interesting.
>The EPC is divided into sections, three of which hold information:
>
>28 bit Manager Class:  unique identifiers for 268 million companies
>24 bit Object Class:  16 million (for each company)
>36 bit Serial Number:  68 billion (in each class)
>
>Thats a total of 88 bits of useful info, which suggests a total of
>3e26 numbers (2^88).
>
>A ridiculously large number, yet apparently it isn't big enough - a
>tag with a 256 bit EPC has been proposed:
>64 bit Manager Class:  18 quintillion companies (1.8e19)
>56 bit Object Class:  72 guadrillion product types (7.2e16)
>128 bit Serial Number:  340 undecillion unique product numbers (3.4e38)
>
>Taken together, thats 248 useful info-containing bits which could
>identify 4.5e74 objects.  Let me restate that:
>
>450 billion vigintillion objects.
>
>However, its still less than the number of atoms in the universe (more
>than 4e79), and quite inadequate for, eg, counting all the neutrinos,
>photons, etc.
>
>  
>
Yet fits nicely into a long tradition of technical underestimation eg 
"all anyone will ever need is 640K of memory", or "32 bits of  TCP/IP 
address is enough to give every person on earth their own, why would we 
need more?"

As for that 450 billion vigintillion objects, let's hope that the 
technology never has to be extended to label virtual states in quantum 
computers (for some totally unknown reason). It may prove grossly 
inadequate.

-- 
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org



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