[ColorForth] Why I'm Here

[Roger Ivie <IVIE@xxxxxxxxxx>]

Arthur W. Green wrote:
> Can anyone tell me if there is any particular reason why we couldn't just 
> ditch most of the USB standard and just use a single port on a bus (if
>  multiple ports exist per bus) as a high-speed serial port and forget all 
> about device sharing and the like on a typical PC?

My personal gripe about USB is that it seems like Intel did things
differently just to be different. The stuff USB is doing could be done
just as easily with something like HDLC which has been available 
off-the-shelf for decades. Had Intel not used a new whacky bit-stuffing
algorithm and CRC polynomial for the commands (which are different from
what USB uses for data, BTW), they wouldn't have had to invent any
hardware at all; the electrical interface seems to be pretty similar
to that offered by the antique 26LS32, but I'm no expert.

But all that aside, bear in mind that USB isn't really a bus. When your
computer speaks USB, it's talking point-to-point to the USB hub, which
is then passing the data along to the appropriate device. If all you want
is a high-speed serial interface to a single device, just plug it right
into the PC and forget about supporting hubs.

All this is complicated, of course, by the fact that many USB devices
include an integral hub. If you want to talk to a USB keyboard, you'll
probably find it implemented as a hub in front of he keyboard; that's
what lets you plug the mouse into the keyboard.

If you're willing to do your own thing, you might take a look at
IEEE 1355, which is the standardization of the old Transputer
communication links. See http://www.1355.org/. Being an IEEE standard,
they want you to pay for a copy of the document. However, they do have
copies of the data sheets for old chips that implemented the Transputer
links. Look under "archive".
-- 
Roger "Deranged Lunatic" Ivie
ivie@xxxxxxxxxx
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