A: Boston, Massachusetts, United States
During 1983 and the first part of 1984 Phoenix Technologies, then in Boston, Massachusetts, created the first commercially available IBM PC compatible ROM Bios. Licensing of this firmware interface allowed a computer to run the same operating system and the same applications as the IBM PC, and enabled the rapid expansion of the IBM PC compatible computer industry.
To defend against the inevitable copyright infringement suits expected to be brought by IBM, Phoenix engineers reverse-engineered the Bios using clean-room design, in which the software engineers had never read IBM's reference manuals:
"Phoenix developed a 'clean room' technique that isolated the engineers who had been contaminated by reading the IBM source listings in the IBM Technical Reference Manuals. The contaminated engineers wrote specifications for the BIOS APIs and provided the specifications to 'clean' engineers who had not been exposed to IBM BIOS source code. Those 'clean' engineers developed code from scratch to mimic the BIOS APIs. This technique provided Phoenix with a defensibly non-infringing IBM PC-compatible ROM BIOS. Because the programmers who wrote the Phoenix code had never read IBM's reference manuals, nothing they wrote could have been copied from IBM's code, no matter how closely the two matched" (Wikipedia article on Phoenix Technologies, accessed 01-01-2013).