Date: Thu, 11 Jul 2002 02:41:22 -0600 (MDT)
From: "M. Warner Losh" <[EMAIL PROTECTED]>
Subject: Re: [LIB] L50 & USB?

In message: <[EMAIL PROTECTED]>
            "neil barnes" <[EMAIL PROTECTED]> writes:
: I think that's the maximum rate the processor can get data to the bus. 
: There's no DMA AFAIK, and it's a slow 16-bit bus. It doesn't cause errors on 
: even a 100M network card, it just can't use all the available network 
: bandwidth (though the data it gets is still noticably faster than with a 
: 10M).

There is a DMA standard for 16-bit PC Cards, however almost none of
them implement it because the bridge chipsets have so many weird ways
of doing DMA the Windows based "enablers" supported it badly.

But you are correct that it is bus bandwidth issues that limit the
speed of the PC Cards.  Either the host bus is the bottle neck (if the
bridge is on the ISA bus) or the timing specs of the 16-bit PC Cards
causes the limit.

Warner



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