(j3.2006) [Fwd: Re: Ms. April Hollerith's new data compression algorithm]]

[Tom Clune]

I was expecting this email 15 days ago.   Is the delay because of the mail server?

- Tom

On Apr 16, 2015, at 3:18 PM, Van Snyder <Van.Snyder at jpl.nasa.gov> wrote:

> 
> > http://thememoryguy.com/new-algorithm-dramatically-reduces-storage-power-requirements/#more-1112
> 
> >         A lone inventor has developed a data compression algorithm
> >         that defies the theoretical ?Shannon Limit?. The press hasn?t
> >         covered this recent news, even though it has dramatic
> >         implications. This is probably because the technique is so
> >         very arcane. The inventor is none other than the
> >         great-great-great granddaughter of the inventor of the
> >         tabulated punch card, Herman Hollerith.
> >
> >         The algorithm reduces most of the data while converting the
> >         remaining information into as many ones as possible. This not
> >         only shrinks storage requirements and costs, but in the case
> >         of flash memory, it also has an important impact on total
> >         power. Flash is erased by setting all bits to ones, and bits
> >         are written by either leaving them alone (one) or by changing
> >         them (zero). The fewer zeros in the code, the less energy
> >         required to change the bits. Energy is also saved during an
> >         erase, since fewer bits need to be brought back to the erased
> >         state.
> >
> >         To explain the algorithm in its simplest terms, a byte of data
> >         is evaluated. If it has more zero bits than one bits the byte
> >         is inverted and an index bit is set to reflect this fact.
> >         Next, the four bits on either side of the byte are evaluated
> >         and if one has more zeros than ones it is inverted and another
> >         index bit is set. This process continues until all of the data
> >         bits become ones, resulting in seven index bits to represent
> >         the original 8-bit byte.
> >
> >         Since the process can only be performed on even numbers of
> >         bits, the next step is to index the indexes by approaching
> >         them vertically (across eight addresses) one bit at a time.
> >         The least significant index bit of addresses 0-7 are
> >         compressed, then the next most significant bit, etc.
> >
> >         The algorithm repeats the process diagonally across the array,
> >         then diagonally in the other direction. By this time each
> >         address has been reduced back to an even number of bits, so
> >         the original process can start again. After several iterations
> >         the entire data set has been compressed by several thousand
> >         times and the remaining data consists of mostly ones. With an
> >         infinite number of iterations the data could be reduced to a
> >         single bit.
> >
> >         Decompression involves a simple reversal of this process.
> >
> >         The Memory Guy was fortunate enough to be able to speak to the
> >         inventor, Ms. April Hollerith, on the phone.
> >
> >         ?My famous ancestor was highly focused on efficiency. One idea
> >         that he had was to minimize the number of holes punched in his
> >         cards, because this required human effort. Not only was it
> >         tiring to use the original hole-punching machines, but the
> >         more holes that had to be punched, the greater the number of
> >         human errors that resulted.
> >
> >         ?He tried boiling the original scheme down to a number of
> >         index tables and mnemonic devices, but found that the approach
> >         was far too complex for the workers who punched the cards and
> >         later abandoned the concept. From time to time over the years
> >         university researchers have explored the technique, but it
> >         wasn?t until recently that computing power became sufficiently
> >         inexpensive that his 1885 invention could be economically
> >         implemented. Here we are, 130 years later, and this inventor?s
> >         idea is poised to change the world of computing."
> >
> >         When I asked Ms. Hollerith what she intended to call the
> >         algorithm she replied that the Hollerith name was already too
> >         highly connected to the world of punched cards, and would be a
> >         poor choice. This led her to decide to base its title on her
> >         first name. Since the algorithm converts as much data as
> >         possible into ones she has given it the name ?April 1?.
> 
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Thomas Clune, Ph. D. 				<Thomas.L.Clune at nasa.gov>
Head ASTG,Code 606
NASA GSFC		
MS 610.8 B33-C128
Greenbelt, MD 20771
301-286-4635









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