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Name PCMCIA originally stood for Peripheral Component Microchannel Interconnect Architecture. This awkward initialism was jokingly expanded as "People Can't Memorize Computer Industry Acronyms" or "Personal Computer Manufacturers Can't Invent Acronyms". It was then retronymmed to name the standards organization, the Personal Computer Memory Card International Association. Difficulty with the acronym led to the simpler term "PC Card" for the version 2 specification. Card types All PC cards are 85.6 mm long and 54.0 mm wide. The form factor is also used by the Common Interface form of Conditional Access Modules for DVB broadcasts. The 16mm thick "Type IV" card, introduced by Toshiba, was not officially sanctioned by the PCMCIA. The original standard was defined for both 5 volt and 3.3 volt cards. The 3.3V cards have a key on the side to protect them from being damaged by being put into a 5V-only slot. Some cards and some slots operate at both voltages as needed. If your card will not go into the slot, this means you have a 3.3V card and a 5V slot. CardBus cards are 3.3V only. * Type I The original PCMCIA specification cards (version 1.x) were Type I and featured a 16 bit interface. Type I cards were used only for memory expansion. They had a single row of connector pins and were 3.3 mm thick. Type II The Type II PC cards featured a 16 or 32 bit interface, using two rows of pins. They were 5.0 mm thick. Type II cards introduced I/O support, allowing PC cards to attach an array of peripherals. Type III The Type III PC cards were 16 or 32 bit, using four rows of pins. These cards were 10.5 mm in thickness, allowing them to accommodate larger connectors for peripherals without the use of dongles. CardBus CardBus are PCMCIA 2.1 or later (JEIDA 4.2 or later) 32-bit PCMCIA cards, introduced in 1995 and present in laptops from late 1997 onward. CardBus is effectively a 32-bit, 33 MHz PCI bus in the PC card form factor. CardBus includes bus mastering, 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, such as those that support Wi-Fi. 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 new slots are compatible with both CardBus and the original 16-bit PC Card devices. Descendants and variants The interface has spawned a generation of flash memory cards that set out to improve on the size and features of Type I cards: CompactFlash, MiniCard and SmartMedia. For example, the electrical specification for the PC card is also used for CompactFlash, so a PC Card CompactFlash adapter need only be a socket adapter. ExpressCard is a later specification from the PCMCIA, intended as a replacement for the PC card. See also | ||||||||||
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