Sure looks like some monkey business here. This patent was filed in 2011, but it's actually a filed as a continuation. Here's the critical bit:
This patent application is a continuation of co-pending U.S. patent application Ser. No. 12/632,262, filed Dec. 7, 2009, which is a continuation of U.S. patent application Ser. No. 12/168,578, filed Jul. 7, 2008, and entitled DISPLAY SYSTEM HAVING FLOATING POINT RASTERIZATION AND FLOATING POINT FRAMEBUFFERING, which is a continuation of U.S. patent application Ser. No. 09/614,363, now U.S. Pat. No. 7,518,615, filed Jul. 12, 2000, and entitled, DISPLAY SYSTEM HAVING FLOATING POINT RASTERIZATION AND FLOATING POINT FRAMEBUFFERING, which is a continuation of U.S. patent application Ser. No. 09/098,041, now U.S. Pat. No. 6,650,327, filed Jun. 16, 1998, and entitled, DISPLAY SYSTEM HAVING FLOATING POINT RASTERIZATION AND FLOATING POINT FRAMEBUFFERING, the disclosures of which are incorporated herein, in their entireties, by reference.
In short, they get to claim a priority date going back to 1998, as long as at least one patent application in the chain was in pending status when the next was filed, going all the way back to 1998. And that at least one inventor is listed in common. And, of course, that this filing (8144158 is all about the format of their floating point) is really an elaboration on what they did back in 1998, and not something different.
This is a really long time for this kind of thing... and that's just what they were after, of course. At least, under the new patent laws, the filing date and 20 year life are based on the actual filing date. Under the old system, you were given 17 years from the date of grant, so it was common to try to delay the grant date as long as possible, so that the things you did "way back when" were now commonplace. A legal submarine patent. This long string of continuations amounts to much the same kind of thing, though of course, they can't claim something different. For example, the 32-bit or 64-bit floating point units in current GPUs are probably not infringing, unless they derive directly from this design (unless it's determined that the FPU design is in itself obvious, or already covered by prior art). This also means that the 8144158 patent will expire in 2018 along with 6650327, not in 2031, which would be the expiration date of a new patent applied for in 2011.
From the troll company's viewpoint, it could well be that they found a bunch of GPUs out in the market using a design very similar to that of the old SGI GPUs, and decided to file this to enhance their case, which again, is just dandy as long as at least one patent in that long chain was still pending at the time this one was filed. It could be the defeat of the '327 patent against ATi illustrated their weakness going up against other devices.
I wondered who they're specifically after:
Apple iPhone: PowerVR (all. SGX543MP2 in the iPhone 4S)
HTC EVO4G: Qualcomm Adreno 200
LG Thrill: PowerVR SGX540
RIM Torch: Qualcomm Adreno 205
Samsung Galaxy S: PowerVR SGX540
Samsung Galaxy SII: ARM MALI-400
Sony Xperia Play: Qualcomm Adreno 205
So that's basically every GPU maker in a mobile device other than nVidia. And not all that interesting that Qualcomm's on the list, since they're now licensing PowerVR anyway, and so Adreno may be relegated to economy devices, or gone completely in short time. This was probably critical to Qualcomm's reputation, with the Krait-based S4 SOCs, they'll otherwise have the fastest per-CPU-core ARM on the market, at least until A15s are out. No need to hamstring that with the weakest GPU... but I digress.