"ASAAR" <caught@[EMAIL PROTECTED]
> wrote in message
news:ggoko3hourm6hga1chv7pskbdgs20tb8t5@[EMAIL PROTECTED]
> 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
ermm, the data *is* transferred serially.
http://www.interfacebus.com/Secure_Digital_Card_Pinout.html
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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