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Intel Pentium 4


Intel Pentium 4: Image Courtesy of Intel

April has always been one of Intel’s favourite times of year for releasing new processors. Previous April’s have seen some rather memorable chip releases such as the Pentium 166 (1996), the original “Klammath” Pentium II (1997), the first 100 MHz bus compatible Pentium II 400 (1998) and the infamous cacheless “Covington” Celeron 266 (again 1998).

True to Intel’s chip releasing form, they have released their latest high end chip at the beginning of April this year in the guise of the new 2.4 GHz Pentium 4 processor. Will this latest Pentium 4 live up the reputations set by some of it’s illustrious April released forebears or will it just mark another speed bump in the relentless clock speed climb of the Pentium 4?

As most readers will be aware (or will soon be), the Pentium 4 has had a far rougher ride in gaining market acceptance as the best x86 processor available when compared to previous generations of chips such as the original Pentium, Pentium II and early Pentium III processors. This has been in part due to the much publicised rivalry from AMD and it’s highly accomplished Athlon, and later Athlon XP processor ranges. The other part has been due to the change in design marked the migration from the P6 core of the Pentium III to the new NetBurst core of the current Pentium 4.

In a nutshell the Pentium 4 saw the basic processing pipeline rise from 14 stages in the P6 to 20 stages in the Pentium 4. The most noticable effect of this change to the casual observer is a rather large rise in processing latencies (i,e taking 20 clock cycles to complete an instruction as opposed to 14), which lowered the amount of output per MHz when compared to older designs. As a rough rule of thumb, the original 1.5 GHz Pentium 4 was about as fast as a 1 GHz Pentium III. Thus early Pentium 4 chips did not gain the best of reputations.

Recently Intel has taken steps to address issues surrounding the Pentium 4, such as the lack of an affordable and fast platform upon which to run. Market reception of the original i850 chipset and RDRAM combination was weak due to the high cost of the Rambus memory. The cost aspect of this problem was addressed by the PC-133 compatible i845 chipset, but this left users with less than spectacular performance (especially when compared to Athlon based systems). The problem of performance has now been addressed with the new i845D chipset which allows the Pentium 4 to be paired with PC-2100 DDR (Double Data Rate) SDRAM.

The other half of this equation was addressed at the same time as the release of the i845D and was the new 0.13 micron “Northwood” core. The new 0.13 micron core allowed Intel to integrate 512 KB of level 2 cache onto the core thus marking a noticable improvement in performance. The extra high-speed, low-latency cache has had the effect of keeping the memory hungry Pentium 4 adequately fed as well as lessening the effect of a mis-predicted pipeline branching operation and any subsequent instruction stalling.

Overall, the Pentium 4 by early 2002 had matured into a far more credible chip that many had originally accounted for.


Pentium 4 2.2 GHz - Page 2.



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