Hi Uzi,
a cardreader is an external piece of hardware for your computer which you need to read/write to the SD-card. Like a floppydisk and the floppydriver. But then bigger and faster. You can connect it via the USB-port and usb-cable to your computer. In use of the KN you need software, what is on your KN-CD. With this software you can e.g. make backups of your SD-card. In general the access-time of KN-SD card is slower, than the accesstime of Computer to cardreader(SD-card).
Please, search in the archieve, there's a lot of said about that.
Greetings,
Cees