Editing PC Card (section)

=== CardBus ===

CardBus are PCMCIA 5.0 or later (JEIDA 4.2 or later) 32-bit PCMCIA devices, introduced in 1995 and present in laptops from late 1997 onward. CardBus is effectively a 32-bit, 33&nbsp;MHz [[Peripheral Component Interconnect|PCI]] bus in the PC Card design. CardBus supports [[bus mastering]], which allows a controller on the bus to talk to other devices or memory without going through the [[Central processing unit|CPU]]. Many chipsets, such as those that support [[Wi-Fi]], are available for both [[Conventional PCI|PCI]] and CardBus.

The notch on the left hand front of the device is slightly shallower on a CardBus device so, by design, a 32-bit device cannot be plugged into earlier equipment supporting only 16-bit devices.  Most new slots accept both CardBus and the original 16-bit PC Card devices. CardBus cards can be distinguished from older cards by the presence of a gold band with eight small studs on the top of the card next to the pin sockets.

The speed of CardBus interfaces in 32-bit [[Burst mode (computing)|burst mode]] depends on the transfer type: in byte mode, transfer is 33&nbsp;MB/s; in word mode it is 66&nbsp;MB/s; and in dword (double-word) mode 132&nbsp;MB/s.