mpogue@vis01.dg.com (Mike Pogue) (07/17/90)
To continue a thread from comp.arch, concerning patentability of certain common graphics operations: In comp.arch, there was much discussion about the current Cadtrak activity. Cadtrak is the alleged inventor of several graphics concepts, including XOR of a frame buffer. I talked to our law department, and they gave me a laundry list of information that they (and every other company currently paying royalties) would be interested in. Here's the summary: Cadtrak claims that they invented several things in the area of computer graphics. Their patent, reissued as #31,200, was originally filed on January 19, 1976. Based on US patent law, if anybody can show "prior art", i.e. a published (or otherwise substantiated) reference, with a publication date of earlier than January 19, 1975, then Cadtrak would NOT be considered to have been the inventor. Here's what Cadtrak is claiming they invented: 1) XOR of the frame buffer. Any hardware that accesses a frame buffer, using exclusive OR to draw something (line, etc.). Drawing the same thing again, also in XOR mode, erases the thing from the screen. They claim that although this is obvious now, that it wasn't back then, and nobody previously had done exclusive OR on frame buffers. 2) Hardware PAN. Any hardware that allows you to change a pointer, and give the effect of panning across an image larger than the actual physical screen. 3) Hardware split screen. Any hardware that allows you to specify two such pointers, such that you can look at two virtual frame buffers on one screen. Of course, this applies to more than two, and it applies to horizontal split, vertical split, and windowing. 4) Double buffering. Any hardware that provides for two virtual buffers, with one being viewed at any one time. Again, this is very similar to the Hardware PAN and Split Screen claims, in that there are pointers that can be used to quickly change what shows up on the screen. 5) Hardware ZOOM, using pixel replication. Any hardware that permits zooming in on an image, by replicating the pixels in a square pattern to make them appear bigger. Anybody who can provide a reference to an article, paper, film, or lab notebook referring to these concepts, and dated before Jan 19, 1975, will become famous (well, OK, almost famous), by stepping forward. My guess is that there are many millions of dollars in royalties involved here, not to mention the basic freedoms in question here. E-mail direct to me is chancy, at best, so best to post the reference, if possible. The future of graphics is in the balance! (Well, it sounds good, at least....) Mike Pogue Data General Corp. Speaking for myself alone, not my company.
rick@hanauma.stanford.edu (Richard Ottolini) (07/18/90)
In article <646@dg.dg.com\ mpogue@dg.dg.com writes:
\ Here's what Cadtrak is claiming they invented:
\1) XOR of the frame buffer. Any hardware that accesses a frame
\2) Hardware PAN. Any hardware that allows you to change a pointer,
\3) Hardware split screen. Any hardware that allows you to specify
\4) Double buffering. Any hardware that provides for two virtual buffers,
\5) Hardware ZOOM, using pixel replication. Any hardware that permits
Our Sun technical contacts in 1985 and 1986, when Sun was a smaller,
always claimed they never implemented these features for patent reasons.lee@rocksanne.uucp (Lee Moore) (07/19/90)
RE: Cadtrak patent
The Xerox Alto computer had what were called display control blocks (DCBs).
The display controller would go thorough a linked list of blocks of bitmaps
and display them sequentially. The first bitmap block would be at the top,
the second right below it, and so on. The first Alto was created in 1973.
The history and design of the Alto are described in a report called:
Alto: A personal computer
by C.P. Thacker, E.M. McCreight, B.W. Lampson, R.F. Sproull and D.R. Boggs
Xerox Palo Alto Research Center (PARC) report # CSL-79-11
--
Lee Moore -- Xerox Webster Research Center -- +1 716 422 2496
UUCP: {allegra, cornell, decvax, rutgers}!rochester!rocksanne!lee
Arpa Internet: Moore.Wbst128@Xerox.Comcavrak@uvm-gen.UUCP (Steve Cavrak,113 Waterman,6561483,) (07/19/90)
From article <646@dg.dg.com>, by mpogue@vis01.dg.com (Mike Pogue): > > Anybody who can provide a reference to an article, paper, film, or > lab notebook referring to these concepts, and dated before Jan 19, 1975, > will become famous (well, OK, almost famous), by stepping forward. My > guess is that there are many millions of dollars in royalties involved > here, not to mention the basic freedoms in question here. > Well, as a starting point for a literature search, I'd try William M. Newman and Robert F. Sproull, Principles of Interactive Compuer Graphics, McGraw Hill, New York, 1973. Although they do not have anything directly relevant, they have several comments on relevant technologies, and a very good bibliography. At the other end, you might check out just what Jobs and Woziack had in mind when they build the Apple. Ditto work at PARC. See ya Steve