Chipsets: - JMU



Chipsets:

A Breakdown of the Evolution, Types and Functions of the Boss of the Motherboard

CS – 350 – 2: Computer Organization and Architecture

Spring 2004

Authors:

Andrew Kennedy

Adrian Romano

Pat Robertson

Table of Contents

Introduction: What is a Chipset? 3

Evolution of Intel Chipsets 3

Triton Series 3

440LX-450NX 4

800 Series 5

Chipset Types 6

Intel Based Systems 7

AMD Based Systems 8

Functions of the Chipset 9

Processor Support 9

Cache Support 10

Memory Support 10

Peripheral and I/O Bus Support 11

Embedded Features 11

Summary 12

Appendix 13

Introduction: What is a Chipset?

In today’s modern personal computer systems, the motherboard is the central site of computer logic circuitry. Without a motherboard, a computer is nothing more than a number of independent, unconnected hardware devices with no means of coordinating with each other. Thus we see that the main function of the motherboard is to provide a platform on which all of the major devices of the computer can connect and communicate with one another. The motherboard also holds the most important microchip in the entire machine: the CPU. So what does this have to do with the chipset? The answer is rather simple. The chipset is what defines the motherboard’s capabilities. Furthermore, it defines the entire system’s capabilities; every major component in the computer—including the CPU itself—is reliant on the functional capabilities of the chipset. Just as the computer is useless without the motherboard, the motherboard is useless without a chipset, hence our nicknaming of the chipset as the “boss of the motherboard.”

The chipset is actually designed around the specifications for a given CPU, therefore the CPU is designed before the correlating chipset(s). This is why many chipset manufacturing companies have begun to design and manufacture CPUs, and vice-versa. For example, take a look at Intel, one of the leading manufacturers in today’s market. Intel is a leader because they have successfully designed and manufactured both CPUs and chipsets (among other devices). Clearly we can see that if the CPU’s functionality is dictated by the chipset, then the chipset must contain a great deal of information about how the computer is meant to work. What is truly remarkable about the chipset, however, is that it not only defines the computer system, but also controls a large number of tasks itself.

Evolution of Intel Chipsets

Though there are many chipset manufacturers in today’s market—SIS, VIA and Opti, to name a few—the chipsets that Intel produces are the most widely used in modern computer systems. While each individual company has made their own mark on the evolution of chipsets, we can best understand the origins of this component by analyzing the development of one particular manufacturer’s products. For this reason we will focus solely on the evolution of Intel’s chipsets from the 1995 Triton series through the release of the 845.

Triton Series

Starting off in early 1995 was the release of the 82430FX, also known as the Triton 430FX. This was the first in Intel’s Triton series. The major technology advances that were incorporated into the 430FX included the PCI 2.0 specification, EDO memory configurations of up to 128MB, pipelined burst cache, and synchronous cache technologies. This chipset was lacking in some areas though. There were several new technologies that were being developed that it did not support including SDRAM, USB and Concurrent PCI. This eventually led to the replacement of the 430FX in 1996, a little more than a year after its launch, by a pair of more advanced and higher performance chipsets; the 430HX and the 430VX (PC Tech Guide, 2003).

The 430VX chipset was designed more for the home user and the 430HX, in turn, was developed more for business. First off, the 430VX addressed the immediate issues the 430FX did not employ—universal serial bus (USB) and Concurrent PCI standards. Not having Concurrent PCI was a serious problem in the 430FX because whenever a bus master, such as a network card or disk controller, tried to transfer data over the bus, the bus locked up in order to have a clear path to memory. This was inefficient because it interrupted other processes that were transferring data, and the full 100MBps of the bus was not being utilized. With the addition of Concurrent PCI, if a bus master was idle, the chipset took control of the PCI bus to give other processes access. It used a timeshare method and increased data transfer rates by 15% from the 430FX. Its focus, as stated earlier, was on the home user. Because of this, the 430VX was designed to speed up multimedia and office applications by supporting SDRAM, which was optimized for intensive multimedia processing. An advantage to SDRAM, besides the performance gains, was that it did not need to be installed in pairs. As for the 430HX, the more business-oriented chipset, the upgraded features improved or allowed networking, video conferencing and MPEG video playback. It also supported multiple processors, was optimized for 32-bit operation, and worked with up to 512MB of memory. It did not support SDRAM, but it did supported error control (ECC) when 32-bit parity SIMMs were used. The main difference between the 430HX and 430VX, however, lied in the packaging. The 430VX had four separate chips, which were built using traditional plastic quad flat packaging. The 430HX included just two chips, the 82439HX System Controller (SC), which managed the host and PCI buses, and the 82371SB PIIX3 for the ISA bus and all the ports. The PIIX3 provided two buffered serial ports, an error correcting Enhanced Parallel Port, a PS/2 mouse port and keyboard controller, a USB connector, and an infrared port (PC Tech Guide, 2003).

Following the 430VX and 430HX came the more advanced Triton 430TX. It still incorporated many things its predecessors had—such as Concurrent PCI, USB support, aggressive EDO RAM timings and SDRAM support—but it was optimized for the newly developed MMX processors for use on both desktops and laptops. The architecture follows the model of the 430HX with the two-chip format, the 82439TX System Controller (MTXC) and the 82371AB PCI/ISA IDE Xcelerator (PIIX4). Figure 1 in the Appendix shows a diagram of what this architecture looks like. Other advances included the use of Dynamic Power Management Architecture (DPMA), which provided a reduction of the power the system consumes. It also offered intelligent power-saving features like suspend of the RAM and disk. There was also a speed increase in the data flow from the hard disk to 33MBps by way of Ultra DMA protocol (PC Tech Guide, 2003).

440LX-450NX

Next we come to the 430LX (not the Triton 430LX because the name Triton was dropped). It was designed specifically for the recently released Pentium II processor and incorporated many of the same features as the 430TX. These included SDRAM and Ultra DMA support. The main hurdle the 430LX conquered was the bottlenecking from the graphics controller and system memory to the CPU. To solve this, Accelerated Graphics Port or AGP was developed. AGP was a fast, dedicated bus directly from the graphics controller to the CPU, which aided fast, high-quality 3D graphics. Another feature was the Advanced Configuration and Power Interface (ACPI). This provided quick power up and down, remote start-up over a LAN for network management, and included temperature and fan speed sensors (PC Tech Guide, 2003).

Following the release of the Pentium II, the Celeron processor was developed as a lower-cost alternative. The 440EX was developed around this and had all of the same features as the 430LX for a smaller price tag (PC Tech Guide, 2003). By 1998, the CPU speeds had become so fast that the system bus could not keep up. Other chipset manufactures overtook Intel in this issue and developed Socket 7 architecture for their motherboards. Intel, of course, followed suit in April of 1998 with the 440BX chipset. The 440BX boasted a 100MHz system bus and SDRAM speeds. It was also backwards compatible so that the older 66MHz bus Pentium II could be used as well. Quad Port Acceleration (QPA) was also added to the 440BX, along with support for dual processors and AGP2x. QPA enhanced system performance by combining enhanced bus arbitration, deeper buffers, open-page memory architecture, and ECC memory control to improve system performance (PC Tech Guide, 2003). The 440BX was later used with Pentium III processors (Intel, 2004).

Not long after the 440BX was released, a new processor was developed—the Pentium II Xeon. With it came the 440GX chipset. See Figure 2 in Appendix for the diagram. The 440GX with Xeon processor was geared toward workstations and servers. It included most of the features of the 440BX like AGP2x expansion slot, dual CPUs and a maximum of 2GB of memory. It also had a backside bus linking the L2 cache and the CPU with a dedicated bus line. This allowed the L2 cache to run at the same speed as the core of the CPU (PC Tech Guide, 2003).

At the same time, the 450NX was released. This was designed specifically for servers and incorporated a 64-bit PCI bus. This enabled a second PCI bridge chip to be added to the motherboard, which was capable of supporting six 32-bit slots, three 64-bit slots or a combination. The reason for this feature was to support devices such as network and RAID cards. The 450NX also supported 1-to-4-way processor operation, up to 8GB of memory and 4-way memory interleaving, which provided up to 1GBps of memory bandwidth (PC Tech Guide, 2003).

800 Series

Now we come to the period of the much more advanced 800 series chipsets. The first in this series, the 810 chipset, had three variants: the 810, the 810-DC100, and the 810E. The 810 and the 810-DC100 were released in the summer of 1999 and were the same except for the 810-DC100 provided for 100MHz processor bus and a 4MB on-board graphics memory while the 810 only ran at 66Mhz and had no graphics memory. The 810E was released soon after in the fall of 1999. The perk to the 810E was that it could run processor bus speeds of 66 MHz, 100 MHz, or 133 MHz (PC Tech Guide, 2003).

In November of 1999, the true power of the 133MHz system bus of the Pentium III was shown with the development of the 820 chipset. The project, which was originally slated to come out with the release of the Pentium III in spring of 1999, hit a roadblock with production of Direct Rambus DRAM (DRDRAM), which was a key component of the 133MHz platform strategy. There were many advantages to RDRAM, one of which being it provided a memory bandwidth capable of delivering 1.6GBps, which was twice the peak memory bandwidth of 100MHz SDRAM systems. The 820 also added AGP 4x technology, which allowed main memory to be accessed by graphics controllers at more than 1GBps—twice that of previous AGP platforms. This, in turn, significantly improved graphics and multimedia handling performance. The 820 differed from earlier chipsets in that it employed a three chip hub architecture. It had a Memory Controller Hub, an I/O Controller Hub, and a Firmware Hub. A diagram of this chipset can be found in Figure 3 of the Appendix. The Memory Controller Hub (MCH) linked the CPU, memory and AGP, and supported up to 1GB of memory via a single channel of RDRAM using 64, 128 and 256Mbit technology. The I/O Controller Hub linked the I/O devices to the main memory, which increased the bandwidth and significantly reduced arbitration overhead. The Firmware Hub stored system and video BIOS, and included the first hardware-based random number generator (RNG) for the PC platform. The Intel RNG used thermal noise to generate truly random numbers that provided stronger encryption. Shortly thereafter Intel realized the price of RDRAM was not decreasing any time in the near future, so they developed a Memory Translator Hub (MTH). The MTH went between the MCH and the RDRAM slots, and translated the Rambus memory protocol that RDRAM used into the parallel protocol required by SDRAM. This allowed the 820 to use lower priced memory (PC Tech Guide, 2003). A few months after the MTH was added to the chipset, a bug was discovered that caused the system to reboot intermittently or hang during operation (Intel, 2001). To correct this problem, the MTH could not simply be removed; a consumer received a whole new motherboard plus the RDRAM to make it work (PC Tech Guide, 2003).

To avoid the fiasco that was the 820, Intel dumped the RDRAM and went to PC133 SDRAM in the middle of 2000 with two chipsets: the 815 and 815E. Both the 815 and 815E utilized the Graphics and Memory Controller Hub (GMCH), which supported both PC133 and PC100 SDRAM. They provided onboard graphics by using a 230MHz RAMDAC, which converted the data in the frame buffer into the RGB signal required by the monitor and provided limited 3D acceleration. This left the option open for using the on-board graphics for lower cost systems, or using an external graphics card via AGP 4x or 2x for advanced systems. In addition, the 815E featured a new I/O Controller Hub (ICH2), which gave greater system performance and increased flexibility. The ICH2 included an additional USB controller, a Local Area Network (LAN) interface, dual Ultra ATA/100 controllers, and six-channel audio capabilities. By including the Ethernet controller directly into the chipset, it was easier for the computer manufacturers to implement low-cost network connections into PCs. The 815E even included a 6-channel audio connection for full surround-sound for Dolby Digital audio formats found on DVDs (Intel, 2004).

In 2001 the Pentium 4 was released, and the 850 chipset was developed along with it. The 850 extended the hub architecture of its predecessors by the new 82850 Memory Controller Hub (MCH). Some of the things the 850 featured were 400MHz front-side bus, dual RDRAM memory channels, 1.5V AGP 4x, two USB controllers (four ports), and dual Ultra ATA/100 controllers. A variant of the 850 was released in fall of 2002, 18 months after the original 850 came out, called the 850E. Everything on the 850E was the same except it supported Hyper-Threading technology, had a 533MHz system bus and worked with PC1066 memory. Hyper-Threading allowed a single processor to be treated as two logical processors (PC Tech Guide, 2003).

This brings us to the final chipset in the evolution, the 845. The 845 addressed the same problem the 820 had: no support for SDRAM. Ever since the Pentium 4 came out, Intel had only provided chipsets with RDRAM. SiS and VIA both released Pentium 4 chipsets that utilized SDRAM, and Intel soon followed suit. The 845, released in summer of 2001, supported PC133 SDRAM. Even though it was significantly cheaper to run a machine with SDRAM, it was far less efficient. The speed of the SDRAM bus was about three times slower than that of the Pentium 4 system bus.

The 845 could have supported the faster DDR SDRAM, but the contract Intel had with Rambus did not allow them to do this until the start of the following year. So, at the beginning of 2002, a new variation of the 845 was released: the 845D. The 845D provided a memory controller that supported PC1600 and PC2100 SDRAM—or DDR200 and DDR266 respectively—in addition to PC133 SDRAM. With the release of USB 2.0 came the release of three more chipsets: the 845G, the 845E, and the 845GL. The 845G incorporated a new generation of integrated graphics called “Intel Extreme Graphics” and targeted the high-volume business and consumer desktop markets. The 845E worked with discrete graphics components, and the 845GL was designed for Celeron processor-based processors.

Finally, we have the 845GE. It was designed to support Hyper-Threading technology and was released at about the same time as the 850E. It also supported a 266MHz version of Intel's Extreme Graphics core, a system bus speed of either 400 or 533MHz, and DDR333 main memory (PC Tech Guide, 2003).

The 845 chipsets by no means marked the end of the evolution of the chipset. In fact, since the release of Intel’s 845 chipsets, a variety of yet more advanced chipsets have been developed, such as the E7205, the 875P, and the 865P, 865PE (Figure 4 in Appendix) and 865G. However, we will now move on to discuss the most prevalent chipset models that one would find in today’s market.

Chipset Types

Chipsets are often based upon certain CPU’s and are designed to work with certain I/O protocols. One chip may be designed for an AMD Athlon CPU with a SCSI interface, while another may be designed for an Intel Pentium 4 CPU using IDE. Since chipsets are designed with a specific CPU in mind, often manufacturers of CPU’s will also build their own chipsets. Intel has been offering its own chipsets since it began offering the Pentium line of processors. AMD began producing its own chipsets around 1997, but still relies heavily on other companies to manufacture chipsets (Newsom, 1997). The manufacturing of chipsets is not limited to Processor manufacturers; other companies have been very successful at producing chipsets as well. For example, graphics card producers, such as Nvidia and ATI, and other companies such as VIA have been fairly competitive in the chipset market. Due to the large selection of chipset manufacturers, the number of different models of chipsets on the market has expanded significantly. This makes finding a chipset with appropriate features for your computer a daunting task. For this reason we will now outline some of the most prevalent manufacturers and models on the market today.

Intel Based Systems

Intel’s significant strength is its size. Being such a large corporation, Intel can manufacture a large variety of chipsets for an array of different purposes. Ranging from low-end home PC’s to high-end graphics and video machines even to the top of the server market; Intel is able to make a chipset to accommodate it’s own Central Processing Unit. Although they are able to produce such a wide variety of chips, that does not mean that they stellar in any one category or are without competition.

As for their low-end offerings, such as the 845 for the Pentium 4 processor, they are often bug free but typically come at a severe performance limitation. This has mainly come from their use of SDRAM instead of more popular and faster DDRAM (Connolly, 2003a). With a larger cost, Intel offers chipsets that can hardly be rivaled in the mid-level computing market sector. For example, the 850 series was one of the most useful chipsets for years. Since Intel should know it’s own CPU best, when they manufacture a high-end chipset, it often is bug free and maximized specifically to perform quickly and efficiently with an Intel CPU (Connolly, 2003a).

In the server and high-end workstation market Intel makes chipsets designed specially for Xeon processors. These chipsets are designed specifically for high-bandwidth uses, using special PCI bus controllers and increased bandwidth for memory channels. Although not designed for server use, the 875P chipset offered a low cost alternative to more expensive chipsets. It lacked some of the features that the higher-end chipsets contain, since Intel intended it to be used for a Xeon processor. This raised questions as to whether it was stable enough to be used as a server chipset, and anytime stability is critical the E7505 should be used. Because it is designed for the high-end server and power workstation markets, the E7505 chipset offers significant bells and whistles such as PCI-X support and a greater amount of Bandwidth between the processors and the chipset. The E7505 chipset is designed to be the most stable server solution available, providing a versatile and effective chipset to run its powerful processor (Connolly, 2004).

Intel has also created a series of chipsets to support its processor growth into 800MHZ Front-Side busses. This series is named the 865 series or “Springdale”. It was originally designed to be the next iteration of the 845 series, and to offer a more cost-effective solution to the 875 series chip discussed above. It is a compromise between cost and performance; it includes some of the less popular features of the 875, but lacks a powerful integrated graphics core. The series is comprehensive, offering the 865P, which is a very low cost chip, the 865G with integrated graphics, and the 865PE, which is a mainstream option in comparison to the 875 series of Intel chips (Shimpi, 2003). The 865 series chipset is detailed in Figure 4 in the Appendix.

Intel has also re-entered the market with integrating graphics on their chipsets. With Nvidia and ATI offering chipsets on AMD based systems; it became necessary for Intel to enter the market to offer a low-end solution that can compete with a similar AMD offering. Their answer to the market was the 845-G “Extreme Graphics” chipset. By doing this, Intel has created a low budget chip that is close to the quality of an Nvidia or ATI offering and also offers Intel’s stability and compatibility. This makes an inexpensive motherboard a greater possibility for IT professionals. Although the integrated graphics of the 845-G cannot compete with an add-on graphics card, it can hold its own in applications designed for word processing and surfing the Internet. Intel has been tried and true in the chipset market for a number of years and has not failed when re-entering the graphics chipset market (Connolly, 2002a).

Intel is not the only manufacturer of chipsets for Intel CPUs, however, other manufacturers are rarely used in mainstream motherboards because Intel does not enjoy competition and has a tendency to sue competitors. VIA and SiS are the most common manufacturers of Intel based chipsets. For example, SiS released the first DDR-333 compatible chipset, named the SiS 645. However, there is a drawback to the chip. With larger numbers of memory sticks, the memory has to be run in DDR-266 mode for the system to be stable. Otherwise the chip proves to be excessively stable for a SiS offering. VIA began producing chipsets for the Pentium 4 without an official license to do so. Because of this, most top motherboard manufacturers would not use the chip, so VIA began to produce its own motherboards to accommodate the VIAP4X266 chip. This chip has proved to be a complete bust, however, with significant bugs, system instability, and compatibility issues. Due to so many companies having bad reputations when producing Intel-based chipsets, it is no surprise Intel still dominates their own market (Connolly, 2003a).

AMD Based Systems

AMD has taken a completely different approach towards chipset design for their CPUs. Rather than try to take hold of the market; they allow competition to spring up and offer a wide variety of chipsets making the CPU more versatile overall. This allows chipsets designed for more specific purposes. Graphics cards manufacturers can design chipsets around integrated video components, providing cheap and powerful onboard graphics. Companies specializing in servers can design chipsets specifically to deal with multiple processors and high-bandwidth devices. Finally, bargain chipset manufacturers can create inexpensive offerings to further lower the cost of a computer at the cost of possible performance options.

VIA has been one of the leading producers of AMD chipsets and continues to lead the way into the new 64-bit processors. Although it developed a reputation for being a cheap and unstable chipset producer, they have recently provided a far more stable and robust set of offerings for the new line of CPUs, for example the K8T800. Mainly this has been due to the forced change in chipset design in the new processor; the memory controller is no longer a component of the chipset, it is included in the processor. Instead of the use of memory being a factor in chipsets, it is now how many additional features can be packed onto a chip that makes it stand out. VIA has been able to provide this in their K8T800 offering integrated video, PCI-X (which doubles the bus of standard PCI), and Serial ATA (SATA). With less focus on memory bandwidth, and an increased focus towards other components, chipsets are becoming less expensive and of higher quality (Connolly, 2003b).

Nvidia originally entered the chipset market to expand on its popular add-on graphics card market. Seeing that not everyone needed a powerful graphics card to use word processors or to surf the web, Nvidia was able to integrate their own graphics technology into a chipset and offer an affordable alternative to buying a low-end add-on graphics card. With the newest processor offering from AMD, Nvidia can escape from its weaker point in memory controlling, and move towards making as robust a chipset as possible. The nForce 3 150 series combines one of the most powerful integrated graphics chips. However, the remainder of their chip does not offer quite as many features as their competitors. It does not offer SATA or PCI-X like the VIA K8T800 (Connolly, 2003b).

To compete with Nvidia, ATI has recently entered the chipset market. Sporting the ATI Radeon IGP 320, ATI partnered with VIA to create an integrated graphics chipset for the AMD XP/MP processor series. Instead of developing their own Southbridge chip, ATI instead out-sourced to VIA to produce circuits that they were not necessarily strong in making. By combining their own graphics expertise with VIA’s years of chipset making experience they were able to make a decent chipset, although it does not outperform Nvidia’s current line of chipsets (Conolly, 2002b).

Functions of the Chipset

The general purpose of the chipset can be compared to that of a traffic policeman. Just as the policeman will guide cars through traffic to their desired destination, the chipset guides the flow of data between the processor, cache, system buses, and peripheral devices of the computer. For a number of years, many of the tasks for which the chipset is now responsible were handled by a much greater number of separate chips; often more than one chip was necessary for even an individual function. Eventually these separate chips were integrated to form a single set of chips, or chipset—usually consisting of two major chips—that implements the assorted control features on the motherboard. It is rare that a chipset will integrate all of the necessary circuitry on a motherboard, however they still control a myriad of functions for the motherboard on which they are contained. In this section we will be discussing some of the most notable functions for which the chipset is responsible, as it would go far beyond the scope of this assignment to document every function performed by the chipset (there are many). The functions are divided into sections relating to chipset support for processors, cache, memory, and peripheral devices. There is also an additional section documenting some of the more important embedded features of the chipset.

Processor Support

The chipset is perhaps the most important factor to take into account when considering what processor to use in your computer. This is due to the fact that the chipset is specifically designed to work with a particular type or class of processors. The reason for this exclusivity is that the control circuitry needs to be designed so that the motherboard can properly support the ways in which the processor accesses memory, cache, and other important system properties. Chipsets will normally support most or all processors within a family, but may also only support one processor in particular. Today most chipsets are designed specifically for one of these four processor families:

• Intel Pentium Pro/Pentium II/Celeron/Pentium III sixth-generation CPUs

• Intel Pentium 4/Celeron seventh-generation CPUs

• AMD Athlon/Duron sixth-generation CPUs

• AMD Hammer-series seventh-generation CPUs

(Thompson & Thompson, 2003).

Another important trait of the chipset is that it delegates what speed the processor is capable of working at. Typically the chipset will control the speed of the processor using two parameters: the front side bus (FSB) speed and the processor multiplier. The FSB, also known as the host bus, represents the speed at which the CPU communicates with the chipset. In modern systems the FSB runs at a speed of at least 66 MHz, however in many systems the FSB will function at speeds up to and surpassing 133 MHz (Thompson & Thompson, 2003). Some recent chipsets have begun to employ a feature called “double-pumped FSB,” which doubles the speed of the FSB as the chipset allows for data transfers during both rising and falling clock pulses. As for the processor multiplier, the internal speed of the processor is found by multiplying it by the FSB speed. Most modern chipsets support multipliers of 3x to 10x and above. It is also important to note that not all motherboards allow for both the FSB speed and the multiplier to be set manually. Some machines will allow for you to set only the CPU speed, and will automatically choose a combination of FSB speed and a multiplier setting to achieve the desired processor speed. This is done in an effort to avoid overclocking, or running the processor at a higher speed than it is capable of. Overclocking can lead to a significant decline in performance.

In synchronous motherboards, setting the FSB speed in turn denotes the speed of the PCI bus. These motherboards, unlike asynchronous motherboards on which the FSB and PCI bus speeds can be set independently, divide the assigned FSB speed by a set number called a divisor to compute the PCI bus speed from the FSB speed. The chipset contains the specification for synchronous or asynchronous systems.

One final processor related function that the chipset is responsible for is the support for symmetric multiprocessing (SMP). SMP is the ability for a single motherboard to employ multiple processors, usually 2 or 4. In order for a motherboard to be able to handle more than one processor, the chipset must have integrated circuitry that directs the data flow of the processors in such a way that they do not hinder each other’s work. The chipset must also be able to organize the workload of each processor by working with the operating system in order to maximize the CPUs’ efficiency. Because of this, SMP is only possible in a system where the chipset, processors, and operating system are all SMP compatible. This property, if executed properly by the system, can greatly enhance a machine’s performance.

Cache Support

The chipset is also an important component in that it integrates features that determine the size, type, and functionality of the system and secondary cache. For example, the chipset is responsible for telling the system how much level 2 (L2) cache it can handle, unless of course the L2 cache is incorporated in the packaging of the processor. Even in this case, however, the chipset will be required to have circuitry that is compatible with the cache.

Additionally the chipset provides the support for which of the major types of cache will be used in the system. The three most prevalent types of cache currently being used are asynchronous, synchronous burst, and pipeline burst, and each of these cache types require diverse logic circuitry. Therefore the chipset is in charge of clearly defining what type of cache will be used.

The chipset must also determine what method of writing to memory the computer will use. In a cache memory system there are two major ways of handling writing to memory: the “write through” method and the “write back” method. Because it is not possible to employ both methods, the chipset must determine which technique the system will use through its logic circuits. Both procedures are used extensively, however the write back method is more popular in the newest computers because it saves time by using less write cycles (at the expense of having the main memory and cache memory more out of sync than when using the write through method).

Finally, the amount of memory that can be stored as cache memory in a system is fully dependent on the chipset. Aside from the question of how much memory the computer can support, the amount of cacheable memory is decided based on the chipset’s control circuitry. This is an important feature of the chipset to be aware of, because if you attempt to use more memory than the system can successfully cache, the system performance will decline dramatically.

Memory Support

The chipset plays a crucial role in the structure and functionality of the computer’s memory. The chipset determines which type of RAM as well as the maximum allowable size of RAM that can be used by the system. Chipsets today are designed with the capability of running up to about 4 GB of RAM. There are a few different major types of DRAM technology that can be employed by the chipset including EDO, BEDO and SDRAM, each of which requires separate logic circuitry in the chipset. While a single chipset may be able to handle more than one of these technologies, it is usually, if not always, designed specifically for one of them. In other words, a chipset that is designed for BEDO may be able to run EDO, however the system will perform noticeably better with the technology that the chipset was designed to run with. The chipset will also specify whether the system will be able to employ SIMMs or DIMMs. The maximum number of slots for additional RAM is also a derivative of the chipset.

Another primary function of the chipset is to act as a go-between for the processor and main memory. The memory controller inside the chipset serves two major purposes. First of all it performs some of the more mundane memory functions in place of the processor without the help of the processor. For example, the chipset may be in charge of refreshing memory. This feature allows the processor to handle more complex functions at the same time, thereby increasing the speed and efficiency of the entire system. The second purpose of the memory controller is to mediate the transfer of data from the processor to the main memory and vice versa.

Peripheral and I/O Bus Support

The chipset determines exclusively what I/O bus standards the motherboard can support and also serves as a mediator between them, the processor, and the main memory. The chipset dictates at what speed each of the I/O busses will be capable of running, and what extra features will be compatible with the system for each of the peripheral devices connected to these busses. The I/O bus standards that are in use today are mainly the Peripheral Component Interconnect (PCI) and, in some cases, the Industry Standard Architecture (ISA). Some chipsets also provide for compatibility with an Accelerated Graphics Port (AGP), which is not quite a bus because it can only support a video card. Typically, a modern motherboard will support around 4 or 5 PCI slots and an AGP expansion slot for a video adapter.

Chipsets also include bridging functions between the I/O busses. These bridge functions allow the devices on two different types of busses to connect together. One example—perhaps the most common type of bridge function—is the PCI-to-ISA bridge. Oddly enough this function connects a PCI compatible device to an ISA compatible device so that they both can then be connected to other system busses such as the memory bus.

Embedded Features

Aside from shaping the different hardware component capabilities, the chipset integrates a vast number of embedded features that are critical to the system’s performance. Many of these features and functions have been standard for so many years that there is little difference between chipsets in their execution. However, some differences are apparent between chipsets of different generations.

One of the standard embedded features on the chipset is the ATA interface that supports four ATA/ATAPI hard disks, two each on two separate channels. The chipset incorporates this interface for a few reasons. One reason is that because these devices are connected to the PCI bus, it will save an expansion slot and therefore reduce cost. Another important feature that may or may not be integrated by the chipset is independent device timing, which allows two different devices on one channel to both operate at the maximum possible efficiency.

Direct Memory Access, or DMA, is another embedded feature included on many chipsets. This allows the transfer of data between devices without passing through the processor. DMA can greatly increase system efficiency because it frees up the processor from having to perform some simple functions that would have otherwise taken up valuable time. This feature can be employed through the motherboard itself, referred to as first-party DMA, or through using a DMA controller fixed on a peripheral device, thus called third-party DMA. The better or newer the DMA controller, the faster the transfers will be. Additionally, the most recent chipsets will provide DMA capabilities for each and every expansion slot on the motherboard.

Another feature that is integrated on most new chipsets is called Plug and Play, or PnP. If the chipset, BIOS, peripheral(s), and operating system are all PnP-compatible, then the system will be able to identify and configure hardware automatically upon installation. Systems that do not make use of this feature are often too difficult and/or costly to upgrade unless the user simply swaps the entire motherboard.

Universal Serial Bus (USB) support is a feature of the chipset that has begun to make a huge impact on the PC universe. It is expected that USB ports will completely replace all other types of ports including serial, parallel, keyboard and mouse ports in the near future.

One final notable feature that is integrated through the chipset is the AGP. The AGP port provides a private channel to connect a video card to the processor. This is a performance enhancement in that it moves the video data off of the memory bus. The AGP has different modes including 1x, 2x, 4x and 8x, listed in increasing order of performance. Today, any system that does not support an AGP mode of 4x or above is considered to be obsolete.

Summary

Chipsets are certainly one of the most important components of a computer; they incorporate many essential components and regulate “traffic” throughout the computing system. Without this vital role, processors would be horribly inefficient and slower components could become choked out completely. A poor chipset can cripple a computer system; it is important to select a good chipset before building a system because chipsets cannot be upgraded like CPU’s or memory. Chipsets cannot be upgraded because motherboards are designed around the chipset, creating the most efficient package possible. From their humble beginnings in the Intel Triton 430FX, chipsets have improved greatly in past nine years. Improving bus speeds, greater clock multipliers, increased memory bandwidth, and integrated video are just some of the additions to chipsets; most of which have improved computers more than the simple clock speed of a Central Processing Unit. Continuing on, chipsets will only become more and more essential to overall system performance. With the next generation of CPU manufacturers moving memory controllers to the processors; chipset manufacturers are now freer to develop faster devices busses, integrate more components, and create a more stable chipset. Whether you build a Intel or AMD based system, it is important to research chipsets so that you can build the most powerful and stable system possible.

Appendix

Figure 1:

[pic]

Figure 2:

[pic]

Figure 3:

[pic]

Figure 4:

[pic]

Works Cited

Connolly, Chris (2002a). “Intel 845-G: The Extreme Graphics Chipset”. URL:

Connolly, Chris (2002b) “ATI Radeon IGP 320 Chipset : Eyeing nVidia’s nForce”. URL:

Connolly, Chris (2003a). “Pentium 4 Chipset Performance Shootout”. URL:

Connolly, Chris (2003b). “The First AMD64 Platforms Compared: AMD, nVidia, and VIA”. URL:

Connolly, Chris (2004). “Xeon Chipsets Compared – 875P Versus E7505”. URL:

Intel (2001). “Intel Memory Translator Hub (MTH) Reboot Issue.” URL:

Intel (2004). “Intel 440BX AGPset Product Overview.” URL:

Kozierok, Charles M. (2004). “The PC Guide.” URL:

Newsom, Billy (1997). “Chipsets: The most important components in a computer system.” URL:

PC Tech Guide (2003). “Chipsets.” URL:

Shimpi, Anad L (2003). “Intel 865 (Springdale) Chipset: Mainstream Dual DDR” URL:

Thompson, Robert B., & Thompson, Barbara F. (2003). PC Hardware In a Nutshell. Sebastopol, CA: O’Reilly & Associates, Inc. TK 7887.5 .T48 2003;

ISBN 0-596-00513-X.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download