usb question


B

badgolferman

My ignorance may be showing but I wonder about this. If your
motherboard is USB 1.1 compatible how would installing a USB 2.0
plug-in card make the card and any peripherals operate at a higher
speed?

Isn't the buss speed of the motherboard the limiting factor? If not,
why was it not compliant with the USB 2.0 standard in the first place?
 
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P

paulmd

badgolferman said:
My ignorance may be showing but I wonder about this. If your
motherboard is USB 1.1 compatible how would installing a USB 2.0
plug-in card make the card and any peripherals operate at a higher
speed?

Isn't the buss speed of the motherboard the limiting factor? If not,
why was it not compliant with the USB 2.0 standard in the first place?

If you install a usb2 card, only the ports on the card will be USB2. It
is am improvement for any peripherals that are usb2 compatible, AND can
communicate above 12Bmbps.

The speed of the PCI bus is much higher than either USB1, or 2, so it's
not the bottleneck.
 
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M

MCheu

My ignorance may be showing but I wonder about this. If your
motherboard is USB 1.1 compatible how would installing a USB 2.0
plug-in card make the card and any peripherals operate at a higher
speed?

Isn't the buss speed of the motherboard the limiting factor? If not,
why was it not compliant with the USB 2.0 standard in the first place?

The bus speed is a limiting factor, *but*

The PCI bus is capable of a top transfer of 132MBps (that's Megabytes
per second).

The USB 2.0 standard allows for a max of 60MBp (often quoted as
480Mbps)

So the PCI bus isn't going to be a limiting factor for a USB card.

The speed of the USB ports on the motherboard is determined by the USB
controller chip.

If a motherboard is determined as only being 1.1 capable, it likely
has a USB controller that's only compliant with the 1.1 spec. As to
why they used a 1.1 compliant controller? Presumably that was the
best technology available at the time the motherboard was designed.
The USB 2.0 spec didn't always exist -- heck, go back far enough and
you won't even find USB ports. Even when the first USB 2.0 compliant
controller chips came out, they were more expensive than the USB 1.1
chips. More recently, the USB 2.0 controllers have become integrated
into motherboard chipsets, so they've become standard equipment --
just as expensive to have them as not.

When you buy a USB 2.0 card, the controller on the expansion card
governs the ports on the card. It doesn't do a thing for the ones on
the motherboard, which are still governed by the controller on the
motherboard.
 

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