Unibus / Qbus bus drivers and receivers

From: Clint Wolff <vaxman_at_qwest.net>
Date: Fri Jun 29 20:53:24 2001

On Fri, 29 Jun 2001, Chuck McManis wrote:

> At 02:04 AM 6/30/01 +0100, Iggy wrote:
> >So, what makes MSCP so particular that it may be patented?
> >And how come people can write emulators and clones all over the place? Haven't
> >Intel or Motorola patents on their processors?
>

The patent protects a very specific portion of the idea, and all
possible implementations of that portion.
A microprocessor isn't patentable. A nifty way of using a stack
for floating point registers is patentable (one of Intel's '387
patents, IIRC). That is why the Weitek math coprocessor wasn't
very popular. It was different from the '387.

You can't get a patent on something that is in the public
domain, or has shipped in a commercial product (even your
own). You can't get a patent on anything published, so most
of the technology from schools is available for free, though
many are starting to create their own patent portfolio for
additional revenue. You can't get a patent on anything the
government paid to help develop.

You can get a patent on stupid stuff if you are lucky and
the examiner isn't skilled in the art. The Y2K fix of adding
an offset to the year is a good example.

Anyway...

The MSCP patent basically covers a single bit that indicates a
buffer is available for use. This is to allow different rate
things to fill and empty buffers independent of each other.
At the time, this was a novel and patentable concept (as
opposed to ring buffers that can only be filled and emptied
sequentially?), and MSCP isn't implementable without it.

DEC licensed the patent to anyone who wanted for $100 a board,
and Emulex, Dilog, and others STILL made a profit on aftermarket
boards. DEC learned(?) from this and wouldn't license a later
bus (VAXBI?), so Emulex and Dilog were limited to purchasing
the cheapest board DEC made, removing the bus interface chips,
and installing them on their own boards. and STILL made a
profit.

Regards,
Clint

> Who knows? Only the patent office I suppose. It was a mass storage protocol
> that DEC invented and some patent examiner said "Yup, this is good stuff."
> The Microprocessor was also patented but that patent has expired. Most of
> the emulators/clones on DEC gear do _not_ include MSCP support. Getting it
> is a challenge. Intel and Motorola have copyrights on their Microcode and
> patents and various aspects of their processors but as a whole they aren't.
> I believe all of Intel's chipsets are patented in one form or another which
> prevents non-licensees from building them.
>
> --Chuck
>
>
>
>
Received on Fri Jun 29 2001 - 20:53:24 BST