PC card
In computing, PC card is the form factor of a peripheral interface designed for
laptop computers. It was originally for
memory expansion, but 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.
Most notebooks used to come with two Type II slots or one Type III. With the removal of legacy ports, most notebooks now only come with one Type II card slot.
PCMCIA cards were designed by the US computer industry to compete with the Japanese JEIDA cards.
Encyclopedia
In computing,
PC card is the form factor of a peripheral interface designed for
laptop computers. It was originally for
memory expansion, but 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.
Most notebooks used to come with two Type II slots or one Type III. With the removal of legacy ports, most notebooks now only come with one Type II card slot.
PCMCIA cards were designed by the US computer industry to compete with the Japanese JEIDA cards. The two standards later merged as
JEIDA 4.1 or
PCMCIA 2.0 in 1991.
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 organisation, 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 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.
Toshiba introduced a 16mm thick Type IV card that was not officially sanctioned by the PCMCIA.
Type I
The original PCMCIA specification cards were Type I. These have a 16 bit interface. They were only used for memory expansion. They have a single row of connector pins and are 3.3mm thick.
Type II
16 or 32 bit, 2 rows of pins. 5.0mm thick. These have I/O support and so can be used for almost any sort of peripheral.
Type III
16 or 32 bit, 4 rows of pins. 10.5mm thick. These are used when extra thickness or bandwidth is important, e.g. storage device, Zip drive.
CardBus
CardBus are PCMCIA 2.1 or later 32-bit PCMCIA cards, introduced in 1995. 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.
External links
