Cutler stopped managing the entire NT project in 1996, but continued to lead the kernel development until 2006. In March 2005, he completed one of his “most gratifying pieces of work” at Microsoft when, partnering with AMD, he helped develop the AMD64 architecture (64-bit extensions to the 32-bit x86 architecture) and led the effort to ship the first two x64 64-bit Windows systems (workstation and server). At the time, some questioned why Microsoft developed a 64-bit system; today most computers are 64-bit systems and even our phones will soon have a 64-bit operating system.