I'm also trying to tell whether they have a Celeron or not. So that's why I'm checking both the manufacturer and the speed so that way I can support both geniune pentium 4s and any future celeron P4 class CPUs. What's the slowest P4 class celeron CPU? Or are celerons still based on the P3? It's been a while since I've kept up on CPUs.
Thanks,
Christian

I just checked and all the info you'll probably need is right here:
 
HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0\
 
The CPU MHz is stored as a REG_DWORD in hex so you'll need to write your program to decode that but the Vendor Indentifer (GenuineIntel, AuthenticAMD, CyrixInstead) and CPU Identifier (x86 Family x Model y Stepping z) are both in plain text. You'll probably need to reference an internal lookup table to make any sense of the CPU Identifier but if you know what you're looking for it shouldn't be all that difficult.

If you do find such a table, please post a link to it, as I am very interested in making sense of the family/stepping, etc... Perhaps others are too?

I have one (at least for Pentiums and Pentium IIs) in my copy of the 10th Anniversary Edition of Scott Muellers Upgrading and Repairing PCs. He probably has a more up to date version (covering Pentium IIIs, 4s and Athlons) in later editions of the book. I don't know of any online resources for the info though but a bit of googling probably would turn up a few...

Thanks Admiral for the registry key. I will have to research and see if it exists in Windows NT 4 and Windows 95 otherwise I'm afraid I can't use it or I will have to provide a contingency plan for the older OS's.
Intel's website has this information, but their site is extremely hard to find information on. I think I will try to write them and have one of their employees find it for me .
Thanks for your help guys,
Christian

Are celerons still based on the P3 instruction set?

Are celerons still based on Pentium II/III Architecture?

Nope, the 1.7Ghz+ Celerons are all based on the Willamette Pentium 4 core just with half the cache of the regular Willamettes (128 instead of 256k).
 
I just checked and the registry key does exist in NT4.0.
 
It's going to be a bit harder under Win9x since the key doesn't hold all the same info. At most you'll be able to get the Vendor Identifer (GenuineIntel, CyrixInstead etc) and what type of chip it is (6x86MX, Model x Family y Stepping z). The clock speed doesn't appear to be contained in the key like with NT. There must be a way to get it though since I'm positive DXDIAG displays the clock speed even under Win9x.

Thank you very much Admiral. I actually don't need the speed I'm just trying to detect whether or not the processor is Intel, and if it is then I need to know if it supports Pentium IV instructions. I'll have to find out about Windows 95. I have Virtual PC and therefore I ought to be able to install it and check. I would just ask someone, but I'd like a Windows 95 test bed for future use anyways .
Thanks Again,
Christian