On a day to day basis, Spillinger [IBM] and his engineers stayed in touch with Jeff Andrews, the Microsoft CPU architect who worked in Mountain View. They argued about many things, but on a technical level. Given the legacy of battles between IBM and Microsoft, everyone knew that they had to be extra careful, and diplomatic, on this project. Microsoft stayed in touch with IBM every step of the way.
“We made the trade-offs together,†Spillinger said. “It started with communication between two teams, and then it expanded so that they talked to any of our engineers.â€
A couple of the trade-offs were big ones. During 2003, IBM realized it had to scale back. Instead of hitting 3.5 gigahertz, IBM decided that it could only target 3.2 gigahertz speeds.
From _Xbox 360 Uncloaked_.