Design Bug Distribution in Pentium 4

Source: EE Times, July 4, 2001
Type of Bug Percentage
"Goof" 12.7
Miscommunication 11.4
Microarchitecture 9.3
Logic/microcode changes 9.3
Corner cases 8
Powerdown 5.7
Documentation 4.4
Complexity 3.9
Initialization 3.4
Late definition 2.8
Incorrect RTL assertions 2.8
Design mistake 2.6
42 Million transistors,
1+ Million lines of RTL
100 high-level logic bugs found
through formal verification