Following in the footsteps of the mobile and server Northwood processors, their desktop Pentium 4 fellows are about to change their core stepping as well. The list of changes in the new desktop C1 core stepping appeared quite long: besides the fewer capacitors on the processor package (their number was reduced from 15 to 12), new S-Spec values, correction of all previously discovered errors, and the changes of the CPUID from 0F24h to 0F27h, the desktop Pentium 4 core acquired a unified VID: 1.525V (it used to be equal to 1.5V for 2GHz+ CPUs, and even smaller for slower processors).

It is very remarkable that Pentium 4 1.6A processor will never get a new core, which means that our recent supposition about the coming discontinuance program for this processor is true (see this news story).

Pentium 4 S-Spec: for old (B0) and new (C1) core
Model	B0 Stepping	C1 Stepping
1.8A GHz	SL66Q	SL6LA
2A GHz	SL66R	SL6GQ
2.2GHz	SL66S	SL6GR
2.26GHz	SL6D6	SL6DU
2.4GHz (400MHz QP)	SL66T	SL6GS
2.4B GHz (533MHz QP)	SL6D7	SL6DV
2.53GHz	SL6D8	SL6DW

The test samples of the CPUs based on the new core are already available for tests, which should be completed by August 23. On August 30 the mass shipments of the updated models will start. These will be Pentium 4 2.53GHz and 2.4GHz with 533MHz QP Bus. And on October 4 they will ship all other models as well. The CPUs working at 2.66GHz and 2.8GHz due within next month are most likely to be based on the new core already.