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

Van Snyder Van.Snyder
Thu Apr 16 15:18:33 EDT 2015

> 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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