Digital Camera Memory Cards

Shipbuilder
3rd July 2005, 12:33
How does a memory card remember digital images?
I know a floppy disk is magnetic and so does not need a power supply to keep its contents.
I know a CD disk has its surface "burned" and also does not require a power supply.

Digital memory cards, on the other hand, are very small and have no moving parts. I can only assume that they have a small battery inside them in order to stores images. If this is the case, the cards presumably have a life span which ceases when the battery runs out. If this is so, how long is the life span of a typical card?

Or do they uses some other method to store images?

I am asking this because I have just discovered that I can use these cards to store normal word processing files and images and as they are a lot smaller than floppies or CDs they are, in many ways, more convenient. However, I would not like to write a very long document on one only to find that it "forgets" the lot before I am finished.

regards

Bob

Shipbuilder
3rd July 2005, 16:33
Thanks for reply Ron. I was not wishing to study how it works, I was simply wondering if it had an internal battery which gave it a limited life. I have been dealing with electronics for many years (ex radio officer), but don't know much about this sort of thing, but I could not (and still can't) understand how it stores info without a power supply. When I got my first digital camera, it came with a 16mb compact flash memory card which was not really big enough for me and I upgraded to 64mb. Then when I got a card reader, I put the 16mb card in it to see if I could save to it from the computer, which I could. Then I tried it for word processing files with images and that worked OK as well. For some applications, it is more convenient for me than floppy or CD provided, of course, that the info on it does not suddenly disappear at some time in the future.

Regards
Bob

airds
4th July 2005, 02:32
I keep all my research information on a floppy (20 actually) but back up with CD, the floppies are for editing which you cannot do on CD


John, if you have a fairly recent PC with USB ports, you'd be better using a memory stick/pen/flash/thumb drive (the name varies) which is a keyring sized solid state storage device. They are tiny and plug into a USB port and simply come up in 'My Computer' as another drive (letter)..

FAR more reliable than any magnetic media like floppies - they have survived washing machine cycles - and with massive storage, from 64 Mb to ~1Gb, which is equivalent to 50-100,000 floppies. Cost? From about 5 upwards ....

Here's a nice 128MB suitable one (http://snipurl.com/amex) (approx.100 floppies) for 8 with free p&p, but you'll find them in your supermarket ......

rdgs

Doug Rogers
4th July 2005, 04:30
John, if you have a fairly recent PC with USB ports, you'd be better using a memory stick/pen/flash/thumb drive (the name varies) which is a keyring sized solid state storage device. They are tiny and plug into a USB port and simply come up in 'My Computer' as another drive (letter)..

FAR more reliable than any magnetic media like floppies - they have survived washing machine cycles - and with massive storage, from 64 Mb to ~1Gb, which is equivalent to 50-100,000 floppies. Cost? From about 5 upwards ....

Here's a nice 128MB suitable one (http://snipurl.com/amex) (approx.100 floppies) for 8 with free p&p, but you'll find them in your supermarket ......

rdgs

Yes they are quite amazing and it seems that they are becoming very popular indeed. Convenient, small, safe and amazing storage capacity for their size. We use them a lot but we also have a portable hard drive that we use for backing up our computers as well, that was a lot more expensive than the memory stick but its storage is unbelieveable for its small size and portability.

Shipbuilder
4th July 2005, 17:17
Thanks for all your replies and information. It has helped a lot. I have looked into saving pictures as TIFFs and as you say, they are not compressed. I didn't know compressing and resaving downgraded jpegs. Although TIFFs use more space, I can put then on a CD as TIFFs and if I require them, can put them back on the computer and change them to jpegs again for emails etc. Also, I can put my 16mb compact flash camera card to good use without having to worry about it forgetting anything, but I also take onboard your advice to back up regularly onto cheap CDs.

Many thanks
Bob Wilson (Shipbuilder)

Old Wilf
16th November 2005, 14:36
The memory card in your digital camera is best kept for use only in the camera. One thing you should never do is delete the images or format it using the computer, there are differences in the way the computer and camera will format the card. Using the computer format progam to format the cameras memory card can result in image corruption or the card not working at all in the camera. I would endorse what others have said about using a flash drive for general use.

Regarding storage life for data most manufacturers say this is about two years and it is wise not to exceed this time. The cards do not use a battery they use what is known as "static RAM" (Random Access Memory) as opposed to "dynamic RAM".
S-RAM when 'written to' remembers what was written D-RAM needs refreshing every few milliseconds. Think of S-RAM as lots of little capacitors that either have a charge or no charge that can be retained for long periods and D-RAM as a set of leaky buckets.

KenLin39
11th November 2006, 13:06
Hi All. 1 GB memory cards are available at " ebuyer.com" priced at 10.50, happy clicking. Ken.