Introduction
Memory cards (i.e. PC Cards) and portable USB disks, known as Jump Drives or memory keys, were not always easy to use as they are today. What was developed for personal desktop computers has been adapted to permit the ease of use you now enjoy with a memory card
Going back a few years will help you to understand the kinds of things that are accepted as "normal" and which today work in the background when you are using your memory cards and are simply taken for granted.
Desktop PC expand easily - you simply add an expansion card when a new product hits the market (today most functions are integrated into the PCs motherboard).
But digital cameras, portable computers, notebooks, hand-held devices, palmtops are "handicapped" - their small size prevented adding a traditional expansion card. This limitation, in particular for PCs and notebooks had produced external adapters, external modems and hard drives, docking stations etc., and these devices limited performance or required bulky external power sources/cables. This is not very practical for mobile computing, or for a digital camera.
A standard, called PCMCIA, for mobile computing was developed and now wide acceptance. This standard was developed jointly in Japan and North America, and is used by just about all manufacturers worldwide who are members of the P.C.M.C.I.A. (Personal Computer Memory Card International Association).
PCMCIA technology, called PC Card, significantly increased the capability of notebooks and hand-held computing devices, and ultimately the digital camera. Digital memory cards and PC Cards provide high performance, easy installation (insert in a slot), and host (computer) independence. They are small and compact like a credit card or even a stamp and can allow "hot swapping." These features have made digital memory cards the standard interface for Digital Cameras and for mobile computing.
TECHNICAL BUZZWORDS
Type I, II, III refers only to the thickness of a digital memory or PC Card; the bigger the number the thicker the card. That’s all-nothing else.
The following may be interesting as "nice to know" information but this all works in the background.
Socket Services is a software in the host computer. Socket Services connects a memory card host controller chipset, such as the Intel 82365SL to Card Services and device drivers. Socket Services manages the memory card socket hardware.
Card Services is a software that coordinates access to memory cards, sockets and system resources. If Card Services is not in the BIOS, the memory ard must come with software that connects drivers to Socket Services or to the memory card host controller.
Tuple is data in the Card Information Structure (CIS) that is used to record information about the memory card. CIS is on every memory card and it contains information about data formatting and organization on the card. We call it the "DNA" of a memory card.
Host Independence is the ability for a memory card to work with any device with a memory card socket.
Hot Swapping is the ability to remove and insert memory cards into memory card sockets without rebooting the PC.
"TYPES" OF MEMORY CARDS
Type I, II & III memory cards look like credit cards or stamps from the top, but have different thickness. All three memory cards, including compact flash cards, have a 3.3mm thick guide rail, but Type II and III PC Cards have "bubbles" that are 5.0mm and 10.5mm thick (a stack of about 7 credit cards), respectively. The guide rails allow the thinner cards to be installed in thicker slots.
Some memory cards such as SD cards, XD Cards, Memory Stick etc. do not follow all the hardware specifications of PCMCIA but rather the SD or MMC Association specifications. Remember, Type only refers to memory card thickness, nothing else.
ADDITIONAL TOPICS ABOUT MEMORY CARDS
DESIRED FEATURES OF MEMORY CARDS
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