Something analogous happened with processors. MIPS had a an instruction set with a couple of patented instructions. Lexra made MIPS compatible chips and didn't implement the patented instructions. Unfortunately they trapped the unimplemented instructions and MIPS successfully argued that since the invalid instruction trap handler could implement the patented instructions the Lexra chip invalidated the patent!
If a Lexra processor encountered an unaligned load or store instruction in the program that it was executing then it did the same thing that it would do for any other invalid opcode, it took a reserved instruction exception. In the second lawsuit between MIPS Technologies and Lexra, filed November 1999, MIPS Technologies claimed that because exception handler software could be written to emulate the function of unaligned load and store hardware, using many other instructions, Lexra's processors infringed the patent. Upon learning of this broad interpretation of the patent, Lexra requested that the US Patent and Trademark office (USPTO) reexamine whether the patent was novel when granted. Almost every microprocessor in the world can emulate the functionality of unaligned loads and stores in software. MIPS Technologies did not invent that. By any reasonable interpretation of the MIPS Technologies' patent, Lexra did not infringe. In mid-2001 Lexra received a preliminary ruling from the USPTO that key claims in the unaligned load and store patent were invalid because of prior art in an IBM CISC patent. However, MIPS Technologies appealed the USPTO ruling and won a favorably broad interpretation of the language of the patent from a judge. That forced Lexra into a settlement that included dropping the reexamination request before MIPS Technologies might have lost its appeal.
One interesting problem with the patent system is that one institution, the USPTO, determines whether a patent is valid but a different institution, the courts, determine whether one infringes. It is entirely possible for the two institutions to interpret a patent differently and for either a non-infringer to be wrongly convicted or an infringer to get away with the crime.
The case of MIPS Technologies v Lexra was ultimately settled out of court and the request for reexamination of the patent was dropped. To this day there is no precedent indicating that processors that execute the MIPS-I instruction set that treat unaligned loads and stores as reserved instructions, such as Lexra's, infringed the '976 patent. The patent expired on December 23, 2006 at which point it became legal for anybody to implement the complete MIPS-I instruction set, including unaligned loads and stores.
After its experience with Lexra MIPS Technologies changed all of its 32-bit cores to use its new MIPS32 instruction set which extends the MIPS-I instruction set to include other features patented by MIPS Technologies. This is similar to Intel's addition of the instruction set extensions to Pentium III in order to prevent AMD from building compatible processors.
Cores from Lexra as compared to cores from MIPS Technologies were smaller, had higher clock speed, had high performance instruction extensions, brought features (such as on-chip debug, MIPS16, write-back caches, MMU, and more) to market sooner, and were less expensive. Despite MIPS Technologies' relatively abundant resources, their product offerings in the market were inferior, their investors wanted to see MIPS Technologies defend its intellectual property, and MIPS Technologies needed to justify the license fees that other companies such as Broadcom, PMC-Sierra, and LSI Logic were paying for rights to use the instruction set for their own processors. This left MIPS Technologies little choice but to sue Lexra, despite a weak case.
Ultimately, MIPS Technologies hurt Lexra's business, Lexra hurt MIPS Technologies' business, and ARM made off with a solid dominance of the IP market. In the court case MIPS Technologies' stalled at every opportunity possible until Lexra ran out of money to fight. Because MIPS Technologies started the game with far more money than Lexra, they outlasted and Lexra was forced into a settlement one week before a trial. Though MIPS Technologies was suing Lexra, the settlement agreement involved MIPS paying Lexra money. The benefit that MIPS Technologies got in exchange was that Lexra exited the IP business. Lexra failed one year later in an attempt to establish itself as a communications chip company during the bottom of the telecom business downturn.
Some Lexra customers disabled the reserved instruction exception for unaligned loads and stores in their chip products. With such a design modification, unaligned loads and stores are treated as no-ops and can not be emulated in an exception handler. MIPS Technologies would have had no claim of infringement against such designs. Despite that, after settling with Lexra, MIPS Technologies threatened legal action against Lexra's former customers. Many companies each found it less expensive to agree to contracts that require payments to MIPS rather than to fight. This strategy by MIPS Technologies is viewed by some as extortion under threat of malicious prosecution.
So at that point the MIPS instruction set was effectively proprietary - you basically had to buy your MIPS compatible processors from MIPS. It's the same with modern x86/x64 - there is another patented stuff (e.g. SSE) in the ABI that you need a license. Right now Intel, AMD, Transmeta and Via have licenses but for example NVidia does not.
Still the odd thing is that x86/x64 is more open than MIPS. So in a way is ARM - Qualcomm could buy an architecture license and build their own ARM core from the ground up that was faster than contemporary ARM designs.
If MIPS had allowed Lexra to do this, perhaps we'd all be using Android devices running on Lexra's MIPS cores.