Is Pentium 4 a 64-bit processor?

[AJana1]

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!

[EstebanA_C_Intel]

Hello Janagewen:

Thank you for contacting the Intel Communities.

In order to make sure which would be the instruction set for a processor, my recommendation would be to check that in http://ark.intel.com/ ARK | Your Source for Intel® Product Specifications by looking the model number or family (Willamette, Northwood, Prescott, etc).

After finding the processor, you can check this information under "Specifications" in the line "Instruction set".

Regards,

Esteban C

[AJana1]

Hello Esteban C,

Thank you for your reply, but I could not find the information there. Let us take Pentium 4 630 for example, it is a Prescott-2M based Intel 64 processor, the most charming lady in my life for ever. After several simple benchmark on x86 and x64 O/S, I found the performance is really increased under x64, especially for 64-bit integral computing, for which I could make sure it is a real 64-bit processor. So I guess its ALU is a 32-bit double pumped pipelined. When working under Legacy Mode and Compatibility Mode, this ALU leaves off its high half, working like a 16-bit double pumped pipelined one; while only working with 64-bit codes, the ALU turns to be fully utilised. So please allow me further to guess other Prescott based processors, they might all equip a 32-bit double pumped pipelined one, but leave the high half always spinning around for 32-bit Prescott processors, without actual computing at all, or reserved for SSE-like instructions to utilise.

I love processors from Intel badly. So I wonder if there are some related documents for the public.

Best Regards,

Aaron Janagewen

[EstebanA_C_Intel]

Hello Janagewen:

Let me further investigate on this.

I will be providing you with a resolution.

Regards,

Esteban C

[AJana1]

Hello Esteban C,

Thank you in advance!

Best Regards,

Aaron Janagewen

[EstebanA_C_Intel]

Hello Janagewen:

Sure, no problem.

I will keep you posted.

Regards,

Esteban C

[EstebanA_C_Intel]

Hello, Janagewen:

After doing my research on this, I was able to find out that the information requested is not publicly available.

If you require further assistance do not hesitate to contact the Intel® Communities again.

Regards,

Esteban C

[NPiri]

Hi Janagewen.

I own a few Pentium 4 "Cedar Mill" CPUs (model nos. 641 and 661) that are 64bit and they can handle X64 (64-bit) editions of Windows well. The Cedar Mill based P4 processors are slightly newer than the "Prescott" series and both are based on the LGA775 platform but the Cedar Mill P4s generate less heat and use less power than the Prescott based P4s. I also own an Intel D101GGC motherboard that can use either those "Cedar Mill" or "Prescott" CPUs.

[EstebanA_C_Intel]

NoelPG:

Thank you for your input on this thread.

If any additional questions or inquiries are present, feel free to contact us back.

Regards,

Esteban C

[AJana1]

Hello NoelPG,

Sorry for my chasing imaginary love but eventually failed again, eventually I am still single from the very beginning to this moment. If any female in the wish of making friends with some an Asian guy, 32 yrs, do please contact with me. OK, I know Pentium 4 Prescott and Cedar Mill could manipulate x86-64 instructions, but I just have few ideas about its actual ALU, 16-bit (like Northwood when I was in high school, it was almost my girlfriend), or 32-bit. OK, that is no longer important at all. I am just seeking the light of my life with strong will to get my first love.

Best Regards,

Aaron Janage

[EstebanA_C_Intel]

Thank you for sharings your thoughts about ALU related information for those families/codenames of CPUs.

I hope you are doing well Sir.

Regards,

Esteban C