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Author Topic: USB 2 with PCMIA Card  (Read 3246 times)

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MACATTACK

  • Guest
USB 2 with PCMIA Card
« on: January 26, 2005, 08:47:02 PM »
Question on my laptop which has only USB 1, if I use a PCMIA USB 2 card with my external USB 2 hard drive what will my transfer speed really be if I have a 133 buss speed?  Certainly slower that the 480Mbit USB 2 standard.  OK Wizards whats the math? HOW Fast

Computer_Commando

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Re: USB 2 with PCMIA Card
« Reply #1 on: January 27, 2005, 08:23:33 AM »
Is your PCMCIA 16-bit, 32-bit or 32-bit CardBus?  CardBus has Max bandwidth of 132 MB/sec.  8 bits in a byte, so multiply by 8.  132x8=1056.  Actual transfer speeds will be far less, just as USB 2.0 will never transfer your files at 480Mb/sec.

CardBus is a direct link to the PCIBus.  PC Card is the same as expansion card in your desktop, so 2.0 on destop and PC Card in laptop are the same.

From http://www.pcmcia.org/papers/new_bus.htm

PC Card-16 cards use an 8- or 16-bit interface that operates at ISA bus speeds (8 MHz) using an ISA-like asynchronous protocol. In contrast, CardBus provides a 32-bit multiplexed address/data path, which operates at PCI local-bus speeds of up to 33 MHz, yielding a peak bandwidth of 132MB/sec. CardBus accomplishes this by adopting the synchronous burst-transfer orientation of PCI, as well as a bus protocol, which is essentially identical to that of PCI.