Re: [CAD_CAM_EDM_DRO] Re: EZ-USB

Smoke wrote:

> I understand from a technician I recently spoke to that works for Gateway
> that the USB ports are one of the WORST problems they have with all their
> machines.
>
> Could this possibly be due to the boards they use or is it something
> prevalent on all machinbes?
>

There's noting wrong with the hardware. Do you remeber the problems with
trying to configure 8 ISA cards in the old PCs, with only 5 interrupts, 4 DMA
channels, and constantly interfering I/O port addresses? ANd, then they
came out with Plug-n-Play, that took 2 years before it even started to work
right? Well, USB is the same, only you have all sorts of (inexperienced) people
buying keyboards, mice, printers, scanners, digital cameras, modems, ad
infinitum, and plugging them in to their computers. Well, some of these devices
were carefully programmed and tested extensively, and others were programmed
by two guys in a garage, and tested with 2 computers, 2 different keyboards
and one printer, and declared totally compatible! Fat chance!

The standards are COMPLEX beyond belief, USB is really a master-slave
network, with device polling, data transfer, interrupt requests, flow-rate control,
all happening over a multidrop serial link, and it is designed so devices can
be added and removed from the network while everything is running.
Not easy to take all possible conditions and state transitions into account
until you have seen them cause a problem.

I'm sure that the manufacturers will eventually figure out what things they need
to do to make the system more robust, but you can't expect everything to go
right at the start.

Jon