The PCMCIA is the Personal Computer Memory Card International Association, an industry trade association that creates standards for notebook computer peripheral devices.

The best known such devices are known as PC Cards (formerly PCMCIA cards). A later revision of the PC Card is known as CardBus. The PCMCIA is also developing a new notebook peripheral specification called Newcard or ExpressCard.

Type II and III PC Cards. The Type III is twice the thickness of the Type II.

PC Card

A PC Card is about the size of a credit card. There are three different sizes, varying in thickness: Type I is 3.3mm thick, Type II is 5.0mm thick and Type III is 10.5mm thick. All are 85.6mm long and 54.0mm wide. Most notebooks take two Type II cards or one Type III.

As per the original name, the first PC Cards were for memory expansion. However, the existence of a usable general standard for notebook peripherals led to all manner of devices being made available in this form. Typical devices include network cards, modems and hard disks.

The electrical specification for the PC Card is also used for CompactFlash, so a PC Card CompactFlash adapter need only be a socket adapter.

CardBus

The original PCMCIA bus is 16-bit, similar to ISA. CardBus is effectively a 32-bit, 33MHz PCI bus, in the same physical form as the earlier cards. The notch on the left hand front of the card is slightly shallower on a CardBus card so a 32-bit card cannot be plugged into a slot that can only accept 16-bit cards. Most slots are compatible with both the CardBus and the original 16-bit cards.

CardBus includes the bus mastering ability, which allows a controller on the bus to talk to other devices or memory without going through the CPU. Many chipsets are available for both PCI and CardBus cards, such as those that support Wi-Fi.

Newcard/ExpressCard

The PCMCIA is working on a replacement for the present card, to be called Newcard or ExpressCard. It uses PCI-Express and is physically smaller. Dell Computer said it would start shipping machines using Newcard in the second half of 2004. [1] (http://www.pcworld.com/news/article/0,aid,114876,tk,dn022304X,00.asp) And Hewlett-Packard actually did it. [2] (http://www.pcmag.com/article2/0,1759,1706542,00.asp)

External links

• Personal Computer Memory Card International Association (http://www.pcmcia.org/about.htm)
  • PC Card overview (http://www.pcmcia.org/pccard.htm)
  • PC Card standard (http://www.pcmcia.org/pccardstandard.htm)
  • CardBus white paper (http://www.pcmcia.org/papers/new_bus.htm)
  • ExpressCard (http://www.expresscard.org/)
  • ExpressCard news clips (http://www.expresscard.org/news.htm)
• Linux PCMCIA Information Page (http://pcmcia-cs.sf.net/)
• PCMCIA/CardBus Linux Status Survey (http://tuxmobil.org/pcmcia_linux.html)

See also

• Information appliance