Frequently Asked Questions
Updated May 17, 2005
The following document contains commonly asked questions regarding PCMCIA, PC Card and CardBus.
There has been much confusion regarding the terminology used to describe PCMCIA and PC Cards. The organization that controls the standard for small form factor memory cards is called PCMCIA (Personal Computer Memory Card International Association). PCMCIA created and maintains the PC Card Standard. The PC Card Standard sets the design and manufacturing standards for several types of PC Cards and the two most common types are the 32-bit CardBus PC Cards and 16-bit PC Cards.Back to top
No, the PC Card Standard describes both 32-bit CardBus PC Cards and 16-bit PC Cards. PCMCIA created and maintains the PC Card standard.Back to top
CardBus PC Cards have an extra metal grounding strip on top of the cards right over the connector. 16-bit PC Cards do not have this connector.
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Check the documentation or specification for your host computer. The slot may also be marked "CardBus". Most notebook computers manufactured after 1998 have CardBus slots. On Windows based computers you can right click on the "My Computer" icon, select "System Properties" and select the "Device Manager" tab. Search for the "PCMCIA Socket" entry and click on it to show the type of PC Card Controller. There should be one entry per slot.
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Yes. Almost all CardBus hosts will accept a 16-bit card.Back to top
No.Back to top
No.Back to top
A 16-bit PC Card is around the same speed as a 16-bit ISA card. A CardBus PC Card is equivalent to a 32-bit PCI Card.Back to top
68 pins. CardBus cards have an additional grounding strip on the top of the card.Back to top
Type I PC Cards are 3.3mm thick. Type II Cards are 5.0mm thick and Type III cards are 10.5mm thick.Back to top
Sycard Technology offers an extender card that allows Type III cards to be inserted into a Type I or Type II slot. The PCCextend 50A is designed for 16-bit PC cards and the PCCextend 70A is designed for CardBus PC Cards.Back to top
In many cases computer vendors limit the user to a Type II PC cards slot because the host slot cannot supply enough power for a Type III PC Card. Damage to the PC Card or PC Card host may result.Back to top
CompactFlash are a smaller form factor card using a 50-pin interface. The CompactFlash standard is administered by the CompactFlash Association.Back to top
Sycard Technology publishes The PCMCIA Developer's Guide. This guide contains information about specification, design and usage information.
The PCMCIA Organization maintains a web site with additional information and directories.Back to top
Try PATCA for technical consultants.Back to top
Currently, all CardBus PC Cards run at 3.3V and 16-bit PC Cards operate at 3.3V and/or 5.0V.Back to top
A 3.3V only PC Card has a low voltage key that prevents insertion into a 5V socket.Back to top
Most CardBus hosts support both 3.3V or 5.0V PC Cards. Older 16-bit PC Card hosts may only accept 5.0V PC Cards.Back to top
If you are looking into the 68-pin connector side of the PC Card, you can see a notch on the right side of the connector. The width of that notch determines if a card is low voltage keyed. The following drawing shows the difference between a low voltage and a 5.0V key.Back to top
While it may be technically possible to get these interfaces working on a 16-bit slot, it probably wouldn't work too well. The 16-bit interface has a maximum theoretical data rate of approximately 20MBytes/second. The actual maximum is probably closer to 1/4 or 1/2 of that (40 to 80Mbits/sec). USB 2.0 is spec'ed at 480Mbits/sec and Firewire is 400Mbits/sec. The data rates of these modern interfaces are too high for the 16-bit PC Card interface and 386/486/P1 class machines. We know of no 16-bit PC Cards that support these modern interfaces. It's time to buy a new computer!Back to top
We are aware of no devices out there that will allow two cards to be supported in a single slot host. While it is technically possible to make such adapter there would be many hardware, software and firmware issues to sort out. A device like that would essentially be a CardBus to CardBus bridge device. The BIOS of the host system may need to be changed to support the additional resources that a secondary PCI-PCI bridge device would require. Power consumption would also be an issue. A single slot computer may not provide enough power to support the CardBus to CardBus bridge and two additional PC Cards. We can envision many situations where this adapter wouldn't work in a particular environment. Not many manufacturers would be willing to market this type of product if it won't work in large percentage of systems. The technical support costs would be too high. So, yes, such a product is technically possible. But it's not really practical.Back to top