I was just at Best Buy and saw several PCI cards that had 4 USB 2.0 ports, claiming of course, to make data transfer several hundred times faster than through a USB 1.1 port. Is that right? You're still using the same PCI bus, so I'm having trouble seeing how this card would increase the tranfer rates. Can anyone explain this? Thanks much!

The PCI bus was not the bottleneck for USB ports so the USB 2 PCI cards apparently do work to allow speeds similar to firewire on USB 2 devices.

Budfred

Thanks Budfred, but I still can't figure the math. The PCI bus runs at 33 Mhz and the claimed throughput of USB 2.0 is 480 Mbits/sec = 60 MB/sec, which is about twice as fast as the PCI bus. Can you straighten me out on this? Thanks. Btw, those cards, at about $40 sound like a deal if they can increase the data transfer rate by a factor of several hundred.

Hi John,
Remember one thing besides the card the devices that you hook up also must be able to use 2.0. So the expense is more than just the hub and card. I use my firewire port if I need high speed transfer since my stuff is not 2.0 compatiable.
Mark:)

From IBM:

"The PCI bus is well-equipped to handle newer, more demanding applications. PCI boasts a 32-bit data path, 33MHz clock speed and a maximum data transfer rate of 132MB/sec."

Since bytes are a grouping of 8 bits, 132MB/sec = 1056Mbits/sec.

Budfred

The problem with USB 1.1 wasn't bus speed, but bandwidth, like Budfred pointed out. USB increases the bandwidth usable by the USB card/controller to a value closer to that of the maximum of the bus.

Bandwidth is a function of the bits wide the bus is and the speed of the bus, so a 16-bit wide bus running at 33MHz is not ging to be as fast a 32-bit bus running at the same speed. Think of them as lanes on a highway. An 8 lane highway is going to be "faster" than a 4 lane, even though the maximum speed limit is the same for each one. Faster here means the actual amount of traffic each highway can handle without significantly reducing the average speed of the vehicles using it.

A quick question...will USB 2.0 work with Windows 98 that is not SE?
Thanks.

Probably with additional software. I would check for updates from MS before investing in it though.

Budfred

The info I got with my USB 2.0 maxtor external drive said 2.0 is up to 40 times faster not several hundred times faster. I don't know if that applies to all USB 2.0 or just that drive.

All usb 2.0 drives

Logically speaking the USB 2.0 port on the PCI card, will run at the maximum thoughput delivered by the PCI slot and not the maximum speed of a USB 2.0 port.

If the maximum throughput of the PCI slot is the same as any other PCI bus, it will not run at that speed because it is more the twice the speed that the USB 2 is capable of.

Budfred

The PCI 2.1 version compliant slot would deliver a data transfer of about 504 Mbps which is sufficient to meet the speed of the USB 2.0 port. So a PCI to USB card will deliver the promised output.

Thanks, all. That really helps!