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