Homebrew PCBs

> The typical approach for using a paralleled port is to write to the port
directly
> without buffering. Most implementations of stepper controllers using USB
use
> either a buffering mechanism or interrupt driven data feed.
> The actual throughput of a high speed paralleled port is on the order of
> 512Kbps. The standard through put of a USB 2.0 port is 480Mbps. The issue
of
> choppiness is one of the OS/Software implementation and not the hardware
> port. The issue arises from the fact that writing directly to the
parallele port is
> much easier than writing directly to a USB port.
> Again, the issue is in the software handling of the port and not the port
speed.


That's what I said, you need extra (and smart) hardware to use USB.  There
is no OS that can handle USB in the same fashion as parallel.

It doesn't matter how fast you can pump bits out the USB port, there is no
guarantee of when they will arrive.  USB is like catching a bus, you wait
for ages then three turn up at once.

Tony