usEnglish       ruRussian       deGerman      

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

Evgenie Rudometov, Victor Rudometov.

< <К началу статьи

The processor of Pentium 4 is taken up a position as the powerful processor oriented to performance of tasks with a minimum quantity of branchings. The applications linked to the Internet concern such tasks, and also tasks of multimedia, for example, value and which share permanently increases. The productivity increase in the given class of tasks was promoted by usage of 128-bit port for operations of floating arithmetics, and also application of 128-bit integer SIMD-operations. New SSE2 commands allow to increase speed of processing of audio-and a video information. Thus new possibilities of the architecture of Pentium 4, including the big length of the pipeline and high frequency operations of the units making the internal arrangement of a kernel, of course, use.

It is necessary to mark, that the high operating frequency has demanded not only radical processing of an inner pattern of the processor, but also depositing of respective alterations in the architecture of the computer and development of appropriate units of the surrounding presented by chips of the system logic — a chip set.

First of all, changes have concerned processor buses — FSB. For anybody not a secret what exactly this important unit of the architecture of system often is a bottleneck in reaching of high values of computer power. Insufficient capacity of this bus is quite often accompanied by insufficient loading of the processor at the expense of appearance of additional cycles of waiting of readiness of the bus. As a result the processor stands idle, that carries on to lowering of efficiency of its operation, and in the total and all system of the computer. Especially it concerns high-powered processors with high values of internal operating frequencies. The given circumstance well-known not only to experts, but also the qualified users.

In struggle for capacity of the bus, and eventually, and the common productivity in the computer architecture there was at first an increase in digit capacity of the bus of the processor to 64 bits, and further and frequency its operations to 133 MHz. However further growth clock frequency is inconvenient, and implementators have selected other path of rise of capacity of the bus of the processor.

Company AMD which in processors Athlon uses high-speed bus Alpha EV6 became the first in retrieval of alternative paths in reaching of high values of capacity of the bus. The given bus carries out data transfer on front and back fronts of clock pulses. It allows to provide at clock rate of 100 MHz data transfer with frequency of 200 MHz, and at frequency of 133 MHz — transmission with frequency of 266 MHz.

Has found the original solution and Intel corporation. Together with the processor of Pentium 4 it inserts the new standard of bus FSB which have inherited the best properties of the predecessors. The new bus of the processor at clock rate of 100 MHz carries out data transfer with frequency of 400 MHz (Quad-pumped — 4X) by transmission and processing of an address part with frequency of 200 MHz (2X). Such organisation considerably increases capacity of the bus of the processor, providing the best equation of system in relation to handle of informational streams. Capacity of the new bus reaches 3,2 Гбайт/c. For matching it is necessary to remind, that the traditional bus FSB used with processors of Pentium III, at frequency of 133 MHz possesses capacity 1,06 Гбайт/c, that, obviously, is an insufficient metric for modern high-powered systems.

However the new standard of the bus has demanded depositing of appropriate corrective amendments in the architecture of the computer and development of appropriate units of a surrounding of the processor, which basis makes a chip set.

As is known, the inner pattern and functionality of chip sets should be closely linked to features of the architecture of concrete variants of processors, with which they are oriented to operation. Implementation of potential possibilities of accessories which processes concern, much depends on these units in videoadapters, dynamic storage units, hard disks etc. Such important parametre of the computer, as a rule, depends on effective operation of components of a chip set also, as productivity.

The first chip set oriented to processors of Pentium 4, became i850, developed and released by Intel corporation. The chip set structure i820, as well as its predecessors, is based on usage of the architecture of a hub which allows to optimise structure of the computer and to accelerate an informational exchange between arrangements with the minimum loading of the processor for similar operations.

As well as in the previous developments of a line of specialised sets i8xx, as the main bus for interconnection of the hubs which are a part of a chip set, the closed 8-bit wire providing capacity to 266 Mb per second is applied. Bus PCI used for these purposes in chip sets of the traditional architecture, provides capacity 133 Мбайт/c. The built in interface of operation with memory (DRAM interface) supports two channels of memory Direct Rambus, appropriate DRDRAM units oriented to usage (Direct Rambus DRAM). At usage of PC800 units and clock rate of the channel of 400 MHz such architecture of a subsystem of dynamic storage provides a transfer rate of 3,2 Gbytes/with. Earlier the transfer rate given data was accessible only in rather expensive systems with a chip set i840 (i840 Chipset) which has been specially developed for high-powered multiprocessors on the basis of processors of Pentium III and Pentium III Xeon, and because of the high price was unavailable to users of computers of type Desktop. The maximum memory size DRDRAM, presented by appropriate RIMM units, can reach 1 values of Gbytes at usage of chips of 128 bits and 2 Gbytes — in a case with chips of 256 bits. Built in structure of a chip set interface AGP ensures functioning of the videoadapter with support of modes AGP 1X/2X/4X (1,5). Thus it can be external or integrated into the motherboard architecture.

Handle of peripheral devices carries out an input/output hub (I/O) — I/O Controller Hub (ICH2), transited approbation in structure before the released chip sets i820E and i815E. The structure of hub ICH2 includes following controllers: the interface with MCH, 2-channel UltraDMA/100 IDE (4 arrangements IDE, reading to 100 Mb per second, writing to 89 Mb per second), 2 USB (only 4 ports), I/O APIC, SMBus, the interface with FWH, LPC (allows to hook up arrangements ISA and X-Bus, such as Super I/O, controllers of the keyboard, the flexible drive, parallel, consecutive ports), AC ' 97 2.1 (to 6 channels of audio), PCI 2.2 (to 6 arrangements PCI), LAN (c Intel 82562EH — 1 Mbit/with HomePNA, Intel 82562ET — 10/100 Mbit/with Ethernet), System and Power Management. The base variant of a chip set i850 consists of three chips: 82850 Memory Controller Hub (MCH) in konstruktive 615 OLGA (13x35 mm), 82801BA I/O Controller Hub (ICH2), 82802 Firmware Hub (FWH).

Systems on the basis of a chip set i850 and processors of Pentium 4 possess high efficiency and wide functionality and are taken up a position for workstations (Workstation) and powerful desktop computers (Performance Desktop). The given systems can be used for solution of the most various tasks, but most brightly possibilities of the new architecture appear in the field of audio-and video information processing. Practically right after declarations of the processor of Pentium 4 and a chip set i850 Chipset the manufacturers traditionally supporting close connections with the corporation of Intel, and, of course, the corporation-implementator of the new processor and a chip set have hastened to show appropriate motherboards. These accessories carry on themselves a print of the new architecture, provide implementation of potential possibilities of the specified units and substantially define computer characteristics. Key parametres of motherboard D850GB of the corporation of Intel the chip set i850 became which basis are more low resulted.

Motherboard D850GB of the corporation of Intel has been created according to guidelines of implementators of the new processor and a chip set. This card became the original standard of motherboards for processors of new and perspective generation of Pentium 4. Considering features of power supplies of these high-powered processors, and also data transfer high speeds, characteristic for the new architecture, manufacturers of motherboards are forced to adhere to the design card D850GB of the corporation of Intel though some and try to make unessential changes and additions became which measurement standard.

More completely possibilities of card D850GB of the corporation of Intel, and also products of some the main manufacturers of motherboards will be considered in one of following articles.

The complete version of given article is published in log "Express electronics" (N4, 2001)

To pass to razrelu Processors