Subject: Re: some observations on the peripheral market
To: None <wb2oyc@bellatlantic.net>
From: Lennart Augustsson <augustss@cs.chalmers.se>
List: port-macppc
Date: 01/11/1999 01:58:19
> Its meant to be a cheap way to put EVERYTHING on, for the home user.
> Period.
Look at figure 3-1 (Application Space Taxonomy) of the USB spec, it
specifically excludes Video and Disk from the USB applications.

> >> the buss....and NOTHING WORKS!
> >One device cannot kill the bus.  That's built into how USB works.  Of 
> 
> Yeah right, and thats what they said about ethernet too!  Doesn't 
> happen much these days, but I was weaned on it, and if you believe
> its not possible you're dreamin'
Have you actually studied how USB works?
75% of the bandwidth may be allocated to isochronous and interrupt traffic
so that places an exact upper bound on how many of those devices
you can have.  The rest is shared between control and bulk; by giving
priority to control you can keep the bus going.  Of course your bulk
traffic can slow down arbitrarily if you connect too many things,
but that's true of any scheme.

> >course, the host controller driver needs to do bandwidth accounting
> >to make sure it doesn't happen.
> 
> Uh huh, and thats never gonna break is that right?  Like I said, when
> it does, NOTHING WORKS!
Of course there host controller software may be buggy, but again that
can happen with any bus.

I'm not saying USB is a panacea, definitely not.  But if you use it
as it was intended I think it will work well.

What do you propose as the alternative to USB?

     -- Lennart