Why are we so stuck on binary multiples for possible sizes?

Discussion in 'iPod touch' started by akm3, Jan 3, 2008.

  1. akm3 macrumors 68020

    Nov 15, 2007
    With 32gb flash memory being so expensive, what is stopping apple from releasing...a 20gb iPod touch. Or a 25.45gb. Or a 19gb.

    Why are we stuck that the next 'hurdle' to jump has to be 32?

    Is that 'just how the chips come'? Does that mean after the 32 we will have a giant hurdle to get to 64? Why not a 48? Or a 40?

    Just confused. I assume it isn't 'one chip' and they use a combination of symmetrical chips, why not use one of the higher capacity ones and one of the lower capacity ones to keep it cheaper, or whatever.
  2. mrgreen4242 macrumors 601


    Feb 10, 2004
    Yes, that's pretty much just how the chips come. However, Apple could use any combination of 2 flash chips in the current touch/iPhone design (as far as I'm aware anyways). Currently the touch has 2x4gb chips or 2x8gb chips. They could go with 1x16gb and 1x8gb for 24gb total... at least that's my best guess, there could be some reason why that's not possible I suppose.

    They could also do a 16+4 (20gb) or 8+4 (12gb) or any combination of 2 from 1, 2, 4, 8, and 16gb... Why they chose to do it with matching pairs is either a technical issue I'm unaware of or just for reasons of buying lots and lots of the same chips at a discount.
  3. bigandy macrumors G3


    Apr 30, 2004
    i'd say that's why. i bet they buy a million 8Gb chips for far less than they could buy half a million 8Gb and half a million 4Gb ones. :rolleyes:

    it's all about the benjamins.
  4. atszyman macrumors 68020


    Sep 16, 2003
    The Dallas 'burbs
    The reason chips come this way is that at any power of 2 for the memory size it's an integer number of bits for the address, any increase in size requires an additional address bit which doubles the number of addresses available. Rather than have to accommodate invalid addresses to the memory chips it's much easier just to double the memory size and have every address be a valid access to the chip.

    For multiple chip setups for total memory it's also a reliability/yeild issue. By only having one type of matched chips, it lessens the possibility of assembly error. What happens if an assembly house inadvertently reverses the 16 GB and 8 GB chip reels? You've either got a lot of rework, or you've scrapped an entire assembly run. If you keep the chips the same then it's one less reel to load in the assembly machine, and if you put in the wrong reel it's just 16 GB iPods instead of 32 GB ones.
  5. eb6 macrumors regular

    Sep 7, 2006
    yo yo yo
    You took the words right out of my mouth.:)

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