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Pentium 4 – a new stage of development of the architecture of high-powered computers

Evgenie Rudometov, Victor Rudometov.

Article is grounded on substances of books "Arrangement of the multimedia computer" and "Motherboards and chip sets"

Development and release of processors of a new generation of Pentium 4 have demanded respective alteration of the architecture of systems that has allowed not only to increase an operating frequency of processors, but also it is essential to raise productivity of computers in multimedia tasks.

The last years critical remarks to the leader of the computer industry of the corporation of Intel are often enough distributed. Problems, of course, are available, but sometimes this criticism becomes cool and carries a shade of some snobbery. Basic backwardness and hopelessness of i440BX architecture and insufficient productivity of the systems created on the basis of a chip set i810, in tasks with a 3D-drawing is marked. Has got also to the solutions providing usage i820 c MTH. Thus critics quite often refer to a recognition implementators of the facts of instability of similar systems. There were no not noticed and processors, long time architectures of a kernel released without change. But paths of implantation of leading-edge technologies and perspective solutions never are lungs. And whether opponents are always right? Whether always their criticism is grounded on the real facts?

Really, glorified chip set i440BX does not support of some the newest functions and specifications, such as, for example, PC133, AGP 4X, ATA/66/100, AC ' 97, Hardware monitoring etc. However manufacturers of motherboards together with the given chip set use additional specialised chips, providing implementation of necessary possibilities, including even RAID. And all it under the comprehensible prices.

By the way, about the prices and methods of their lowering. With that end in view also the variant i820 c MTH, giving possibility of usage SDRAM has been created. Lability of operation appeared only in a number of products at some accessories. And as to systems with i810 the given chip set together with inexpensive processors is oriented to application in cheap office systems where usage 3D-schedules is irrelevant. It is not necessary to compare similar systems to more expensive variants oriented to other usage. However about it quite often forget not only potential users, but also experts. Unfortunately, they are often incapable on advantage to estimate potential possibilities of products accessible to them and the accessories created with orientation to quite concrete usages. Market segmentation is the conventional phenomenon which has found the reflexion in the architecture as processors and chip sets, and other computer units. Segmentation allows to carry out an optimal choice of accessories taking into account a usage of computers and effective performance of tasks in view by them. Thus market requirements permanently vary, that leads to step-by-step offset of products High-End of a class to a low bound, releasing a place to more efficient samples which number the newest processors of Pentium 4 undoubtedly concern. The processor of Pentium 4 earlier known as processor Willamette, is a product with essentially new architecture. It is constructed on the basis of microarchitecture of Intel NetBurst. Contains 42 million transistors. It is created with usage well debugged and checked up on processors of the previous generation of processing technique 0,18 microns though experts assert, that advantages of the new architecture will appear to the greatest degree after transition to processing technique 0,13 microns (2001) and even more at usage of processing technique 0,1 microns (2002) . By some estimations, taking into account perfection of processing technique workers frequency the future models of processors of Pentium 4 can exceed 4 GHz with appropriate growth of their productivity. At the same time it is necessary to underline, that predecessors of these processors have practically reached ceiling frequency, their defined architecture and processing technique. Usage in the architecture of Pentium of 4 processing techniques of a hyperpipelining has allowed to increase considerably an operating frequency, and the first variants of new processors have been released on frequencies of 1,4 and 1,5 MHz.

For support of unceasing functioning of the pipeline of the big length on the big frequency considerable change of the internal architecture of a kernel was required. First of all, it concerns algorithms of a branch prediction. Usage of the improved processing technique of dynamic fulfilment (Advanced Dynamic Execution Engine) improves a branch prediction, raising productivity at the expense of optimisation of sequence of performance of commands. Thus for rise of speed of operation arithmetic-logic blocks (Arithmetic Logic Unit — ALU) work on the frequency doubled in comparison with a kernel. For the processor with internal frequency of 1,5 GHz ALU function on frequency of 3 GHz. It allows to execute some integer commands for the period equal of 1/2 clock ticks.

High efficiency is defined by effective operation of the cache memory of the first (L1) and the second (L2) the levels integrated into structure of a chip of a kernel. As well as for processors of the previous development of Pentium III with kernel Coppermine, the cache memory of second level L2 is hooked up by means of a 256-bit wire (Advanced Transfer Cache). This cache memory has traditional size of 256 Kbytes and works on frequency of a kernel of the processor, providing its high productivity.

For the purpose of optimisation of operation of internal sites of a kernel the instruction set is expanded. In the processor of Pentium 4 the second generation of the commands concerning the expanded set is used. This set representing further development of processing techniques MMX and SSE, has received name SSE2 (Streaming SIMD Extensions 2). Instruction set SSE2 are the stream SIMD-extensions including 144 new instructions, providing still bolshy a performance level on tasks of multimedia on matching with the predecessors of Pentium MMX, Pentium II, Pentium III.

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