4 ms·

Things you should know about USB 2.0 and 3.0

• teilo 17y ago
  And I still do not have an answer to my #1 USB 3 question: Have they solved the CPU utilization and data pipelining / overhead issues? The biggest advantage of Firewire over USB has been the controller which alleviates CPU usage on the host machine, and allows for pipelining of data that makes the protocol more efficient than a given USB connection with the same base data rate. I equip all my Windows machines with Firewire ports for this reason, and use external firewire hard drives for extra storage and for backup. I also have a significant investment in Firewire camera gear, because USB just doesn't cut it for streaming live HD video. However, I would love to abandon Firewire in favor of an optimized USB, if for no other reason that USB has wide industry support, and Firewire seems to be fading away due to its licensing issues.
  • windsurfer 17y ago
    No. There is no direct memory access (DMA) in the USB 3.0 spec. It would be a security nightmare.
    • bdonlan 17y ago
      I'm sure DMA happens between the controller and host - there's no way they could achieve those speeds with PIO. And DMA has nothing to do with pipelining - the controller could easily be programmed with a list of buffers in which to place USB responses.
  • briansmith 17y ago
    Yes, Intel solved it by embedding the controller into all of its CPUs. As a bonus, the controller can be used for general purpose processing too.