[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices ]

System Chipset and Controllers

The system chipset and controllers are the logic circuits that are the intelligence of the motherboard. They are the "traffic cops" of the computer, controlling data transfers between the processor, cache, system buses, peripherals--basically everything inside the computer. Since data flow is such a critical issue in the operation and performance of so many parts of the computer, the chipset is one of the few components that have a truly major impact on your PC's quality, feature set, and speed.

What exactly is a "chipset"? It sounds like something very complex but really is not, although many of the functions it performs are. A chipset is just a set of chips. (He ducks to avoid the flying vegetables. :^) ) At one time, most of the functions of the chipset were performed by multiple, smaller controller chips. There was a separate chip (often more than one) for each function: controlling the cache, performing direct memory access (DMA), handling interrupts, transferring data over the I/O bus, etc. Over time these chips were integrated to form a single set of chips, or chipset, that implements the various control features on the motherboard. This mirrors the evolution of the microprocessor itself: at one time many of the features on a Pentium for example were on separate chips.

There are several advantages to integration, but the two primary ones are cost reduction and better compatibility (the more things that are done by a single chip or group of chips from one manufacturer, the simpler the design is, and the less chance of a problem). Sometimes the chipset chips are referred to as "ASICs" (application-specific integration circuits), which I suppose they are, although there are many other types of ASICs as well.

Note: Intel also calls their chipsets "PCIsets" and "AGPsets", refering to the system bus technologies the chipsets implement.

The system chipset in most cases does not integrate all of the circuitry needed by the motherboard. Most motherboards have the following controllers on them:

• The system chipset itself.
• The keyboard controller, which manages not only the keyboard but also the integrated PS/2 mouse
• The "Super I/O" chip, which handles input and output from the serial ports, parallel port, floppy disks, and in some cases, the IDE hard disks as well
• Additional built-in controllers that are normally found in expansion cards: video, sound, network and SCSI controllers being the most common.

Note: The term "chipset" is also used to refer to the main processing circuitry on many video cards. The name is used because the concept is similar: a highly-integrated circuit used to perform a set of functions. However, this is a totally different type of chipset, and is not the same as a motherboard (system) chipset.

Next: Chipset Functions and Features

Home  -  Search  -  Topics  -  Up