Hello,
There is a question always confused me for a decade! Is EM64T-enabled Pentium 4 a real 64-bit processor?
As is known to us, the integer ALU of the Pentium 4 Willamette and Northwood are double pumped from a pipelined 16-bit execution unit. This double pumped 16-bit ALU is equivalent to a 32-bit ALU. I read many documents and web pages, but I found few about the ALU for Prescott processors. Some rumoured that all the Prescott processors are 64-bit, but early version is directly based on Yamhill project, implementing Intel's own 64-bit version of IA-32, but never enabled for end users. The later version is what we later found on LGA775 platform, supporting EM64T feature. No matter what that rumour is true or not, but the ALU within Prescott processor is still 16-bit but 4 pumped, or 32-bit 2 pumped? All the time, I am so curious about it!