Valvebounce said:
Hi Werz.
I'm sure others will clarify this but CF consistently run at or near their quoted speeds, SD cards write once at or near their quoted speeds, then despite showing as empty once you remove the data they slow right down as they write zeros to each bit before writing the data. This can be overcome by doing a full format which will write the zeros for you. A quick format does not work as this only clears the index (file allocation table). The drawback to this is a full format of a large Gb card will take a long time. Don't remember why CF doesn't have this problem, something to do with all those extra pins SD cards don't have.
That is wrong. Both CF and SD cards are internally the same. Flash memory is organized in "blocks" (individual chips if you want to say so). You can write individual "1" to the chips, but not "0". Instead, you have to delete the data in the whole block, and then rewrite everything again.
That means: If you "format" the card (quickformat or otherwise makes no difference), the card knows that there is no more important information stored in the chips, and the next time you write it will zeroise the first chip, then filling it with your data. That is no problem.
The only big difference between flash and other storage is when you want to change some data. If you change for example a file on your usb drive, the whole block gets rewritten with the new, changed information. The old block gets marked for deletion.
But that is the same for SD and CF (and all other flash memory).
