Re: [CAD_CAM_EDM_DRO] Re: USB on Linux

USB relies on having an intelligent peripheral on the end of the wire,
unlike a 'dumb' parallel port. In this case it would make sense for the
periperal to do the time-critical drive processing as well, removing the
need for critical bus timing and drastically reducing bus traffic. As you
have to have a processor of some sort in the peripheral it would not affect
the price or complexity of the interface to do this.

Les

> The 1 mS per USB frame is correct for the USB that
> is currently available. This is only possible
> for modes that transfer every frame, and these
> modes are limited to small packets. These
> packets are large enough for our purposes, but
> "bulk" mode is used for printers and scanners
> to move large amounts of data more efficiently,
> but with uncertain time of delivery. There is
> a faster USB 2 coming, but I have not yet had
> my hands on it to see if it really helps in
> real time situations.
>
> I agree that USB is harder to use than a parallel
> port, but it is possible. The significance of
> this is changing however as we are fast evolving
> into a world where most users have never seen
> "plain" DOS. The time is coming when it is assumed
> that it is the device must be intelligent, not the
> user. I really do believe that in a couple of years
> finding a new computer with a parallel port will be
> difficult for the average user.
>
> So what is the future? The current standoff seems
> to be between Firewire (Apple/Sony primarily) and
> USB (Intel/Microsoft primarily). USB excels for
> keyboards, mice, modems, printers, etc. whereas
> Firewire excels for hard disks and video. Currently
> it makes sense for a good computer to have both.
> USB 2 is an attempt to change that and it remains
> to be seen if USB 2 will work as claimed and will
> penetrate the market. It will truly be marketing
> that decides, because as with the case of industrial
> computers, unless it is intended for the masses we
> will not be willing to pay the price demanded. All
> of this is irrelevant when talking about surplus,
> please consider my comments in that light.
>
> Cheers,
> Steve Stallings