Updated August 26, 2002
When viewing the PC Card right side up, the area above the pin-outs on the card will have a gold grounding shield strip across it. This strip is necessary to prevent signal noise from interfering with CardBus' high speed (33 Mhz) bus. These 32-bit cards can only be used with 32-bit slots, they are sloted to prevent insertion into 16-bit slots so that the card and the slot won't be damaged by differing voltage requirements. 16-bit cards work in either type of slot, but 32-bit cards only work in 32-bit slots!
The CardBus specification was released in 1996. Typically, any device manufactured before the second half of 1997 will almost certainly not have a CardBus capable slot. The following is useful in identifying if a machine has CardBus slots or call Synchrotech to find out.
Access the 'Device Manager' by the means appropriate to the version of Windows installed. Typically right clicking on the computer icon 'My Computer', selecting the 'Hardware' tab, and clicking the 'Device Manager' button will present the device manager dialog. Scroll to locate an entry entitled 'PCMCIA socket' or 'PCMCIA adapter.' Expand the entry and read the device string that is displayed (two slot machines have two entries). If the string contains the term 'CardBus Controller' like in this illustration, then it has a CardBus bridge and you can utilize CardBus PC Cards. Otherwise, the slot is a 16-bit legacy slot and cannot use CardBus Cards.
Many manufacturers make CardBus controllers, which would appear in the 'Device Manager.' Here are some PCMCIA adapter listings that are examples of CardBus controllers.
Although this information can often be located in the 'Apple System Profiler' application, Apple lists the following machines as being CardBus capable.
The following articles are apropos:
If you have hardware from a non-X86 vendor like Sun Microsystems, it is best to contact them to see if the device supports CardBus Cards. If you are using X86 style hardware with a BSD or Linux variant, you can often determine if a machine has CardBus slots by examining the contents of a dmesg or sysctl -A call.
Only card readers that are 32 bit on a system level bus can handle CardBus. This effectively rules out everything except PCI based readers. Synchrotech sells genuine Elan PCI to PC CardBus readers that can handle both CardBus and legacy PC Cards. Other readers employ combination PCI and ISA to achieve similar functionality. For a full listing of card readers that can handle CardBus cards see: 'Current CardBus Card Readers Available from Synchrotech.' Be aware that there are some card readers that employ CardBus bridge chips, but do not have CardBus capabilities enabled. As far as we are aware, only genuine Elan readers provide both CardBus and legacy PC Card functionality on a single PCI card.
Yes, CardBus slots are completely backwards compatible with Legacy (16-bit) cards.
No, they have groves in the slot guides that are supposed to prevent insertion into legacy slots. Do not try to force a CardBus card into a legacy slot or damage will occur to the card, the slot, or both.
CardBus Cards are closely modeled on PCI. They feature a multiplexed 32-bit data and address bus running at speeds as high as 33 MHz providing a peak transfer rate of up to 132 MB a second. They also have the capability of behaving as system-bus masters. CardBus provides laptops and other devices with high throughput capabilities and expansion for modern buses. The following table illustrates some of the differences between legacy (16-bit) and CardBus Cards.
| CardBus | PC Card | |||
|---|---|---|---|---|
| Address/Data Path | 32 bit | 8 or 16 bit | ||
| Bus Speed | 33 MHz | 8 MHz | ||
| Related Protocols | PCI, Synchronous Burst | ISA, Asynchronous | ||
| Theoretical Maximum Throughputs By Mode | 32 bit Burst Mode | 16 bit memory transfer (100 ns. min. cycle) |
16 bit I/O transfer (225 ns. min. cycle) |
|
| Double Word | 132 MB/sec. | |||
| Word | 66 MB/sec. | 20 MB/sec. | 7.84 MB/sec. | |
| Byte | 33 MB/sec. | 10 MB/sec. | 3.92 MB/sec. | |
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