(j3.2006) [Fwd: Re: Ms. April Hollerith's new data compression algorithm]]
Thu Apr 16 15:25:26 EDT 2015
I was expecting this email 15 days ago. Is the delay because of the mail server?
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
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Greenbelt, MD 20771
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