External card readers are available for different I/O ports
(USB, PCMCIA, parallel, serial). USB and PCMCIA readers should always work.
As far as I know they only support storage media! And therefore
cards can be mounted e.g. /dev/sda1. Be careful with
partitioning and formattings other than VFAT.
There are different kinds of adapters for different protocols (USB, PCMCIA, ..) and form factors (CF, SmartMedia, PCMCIA/CardBus) available.
Some of them e.g. CF to PCMCIA adapters are only physically extending a CF card and don't require a special Linux driver, but the one for the card. Note there are Typ I as well as Typ II (expensive) adapters available.
Just recently PCMCIA to CF adapters came into the market. They convert any CF Type I / Type II slot into a PC Card slot. See Semsons(http://semsons.com/comflastopcc.html).
Others, e.g. the USB Card Reader from
Transcend(http://www.transcendusa.com) work with the usb-storage
module. You are able to mount CF-Cards or SmartMedia cards with this device (note: watch
dmesg).
Other cards than memory or storage cards (like network or modem CF-Cards) don't work with this reader.
If you have an older laptop, which doesn't offer a PCMCIA slot or a laptop, which offers only one slot, you may also use devices (e.g. network cards) connected to the parallel or serial port.
These adapters are used to make a desktop PC usable for PCMCIA cards. Some of the products available in the market are: Quatech ISA to PCMCIA adaptor (PCD2-B or PCD2-F card priced at usd 89) Quatech PCI to PCMCIA adaptor (PCD2-F/PCI-E card) Both the above cards are compatible with Windows 95/98/NT. Other products are XI-600:LANEscape XI-600-XA PCI interface adaptor from ZCOM. For Linux you can find some information and an adapter at Team-Solutions(ttp://www.teampctechnology.com/)
Some readers support all six types at once. Also there are PCMCIA adapters for different cards available.
polld(http://www.cihar.com/software/polld/)
is a simple daemon that periodically opens files defined in
/etc/polld. It can be used for scanning partitions in a card reader that
does not report card insertion and removal.
See here for Linux and SmartCard(TM) readers.