logomacitynet1200wide 1

New G4, which processor?

Speeds up to 1.42 GHz. This is one of the strengths of the G4 update.

But although the speed of the processor (with the drop in prices) is one of the factors on which the marketing of the new machines is based, Cupertino makes very few signs of it. Nor does it, as always, explain to us what processor is in use.

In recent days, when it came to speculating on new products arriving, many have wasted making assumptions about the chips they would use. The most common hypothesis that Motorola would supply Apple with a new semiconductor, called MPC 7457 ,.

According to some Motorola documents leaked on the Internet but never made public, the MPC 7457 is based on the same architecture as the MPC 7455 used until yesterday. Studied as a "bridge" to the G5 (which will have radically different specifications) it would introduce the 0.13 micron circuitry and a second level cache directly on board of the 512 kb chip.

In reality, this last technical detail suggests that this is not the processor used in the new G4. All the machines, as you can see, have only 256kb of second level cache. In addition, Motorola's roadmap places the release of the MPC 7457 in the second quarter of 2003, or from May to June, from which it should be deduced that it is the MPC 7455 of the previous versions.

In reality this too is a mere assumption. Motorola, in fact, does not currently have any 1.42 GHz product in the price list, as if to tell the truth it did not even have any 1.25 GHz. The evolution of the MPC 7455, according to the official documentation, in fact, should stop at 1 GHz (even at 933 GHz according to other sources)

The assumption that both the 1.25 version and the 1.42 GHz version are an "overclocked" MPC 7455 at home by Apple, advanced by some website, does not seem credible. Several resellers of update cards have available 1.2 GHz Motorola processors and if really those used in the CPUs were the result of some particular Cupertino hardware "hack" the producers of upgrading cards would be the last in the world to obtain them.

Much more likely Motorola could have found a way to extend the operating life and speed of the MPC 7455, raising the maximum speed initially expected by carefully studying some refinement not officially declared.

On the other hand, if this had not been the case, in the absence of alternative suppliers (IBM has no competitive PPC in terms of speed with Motorola), Apple would have run the risk of remaining without upgrading since January 2002 (release date of 7455 from 1 GHz) in late spring of 2003 when according to Motorola's roadmap, the MPC 7457 should be released, probably the last "older generation" processor to appear on a Mac Pro, before the debut of IBM's PPC 970 or Motorola's G4 +, chips that are expected to arrive between late 2003 and early 2004 debuting at speeds around 2 GHz

Further on, pending some mention from Motorola, it is not reasonable to suppose.