On Sun, 13 Jan 2008 07:56:55 -0800 (PST), aniramca@[EMAIL PROTECTED]
wrote:
> 1. I wonder about a physical limit in storage for the current size of
> an SD card. How far do you thing that they can squeeze in the amount
> of memory in that size of card? Could it become a 50, 100, 200 GB SD
> card in the future. Why do they multiply in the order of
> 1,2,4,8,16,32, etc. Why not in nice number like 5, 10, 20, 30, 40, 50
> GB, etc (metric)?
>
> 2. On the back of my regular SD card, there are approx. 9 contact
> areas which connect into the terminal.
To access any of the card's memory, data is placed on the address
lines. Whatever a card's memory limit happens to be, if one more
address line is used, the card will be able to address twice as much
memory, minimum. With multiplexed addresses, it could be 4x, or
more. To be able to access memory in nice, round decimal numbers,
the cards and CPUs in the cameras would have to be redesigned to use
a number system other than binary, adding needless complexity.
> Are all those 9 contacts currently utilized for a typical usage in a
> digital camera? Or perhaps that they only use 2-3 contacts and the
> others are just reserves for future use? I noticed similar thing for
> a telephone jack.
If only this small number of contacts was used, the data would
have to be transferred serially, which would be far slower, and
would only really be beneficial if the camera's memory had to be
stored a great distance from the camera. A thin, 50 meter cable
would be much easier to use than a bulky, multi-conductor cable, and
probably much cheaper as well. There are many reasons why this
would be impractical, one being that the longer the cable (all else
being equal), the slower the maximum data rate. But if the cable
was accidentally disconnected from the camera, it would be much to
lose the card/cable if it fell into tall grass. :)
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