Chipsets and Controllers

1. Chipsets and Controllers

2. Chipsets • A chipset is a group of devices combined into one or more integrated circuits (ICs). • Chipsets provide a PC with much of its functionality. • A chipset controls the system bus structures and facilitates the movement of data and instructions between the CPU, cache memory, and internal and external peripheral devices. • The system’s chipset also defines the PC’s possible feature set and peripherals, and plays a major role in its operating speeds.

3. Chipsets • Chipset chips are also referred to as Application Specific Integration Circuits, or ASICs (pronounced ay-six). • However, not all ASICs are chipsets. Some are timers, memory controllers, bus controllers, or digital sound processors, or have other uses. • The term chipset is also used by manufacturers of video graphics cards to indicate the function set on a video card. • The chipset dictates most of the allowable characteristics of the memory that can be installed on a PC’s motherboard.

4. Grouping chipsets • Chipsets are grouped by a number of distinguishing characteristics, such as the socket type of the processor, the generation of the processor, the controllers required, and the number and type of chips in the set. • The two major groupings used for chipsets are • Socket types • North Bridge and South Bridge

5. Grouping chipsets • Socket Types • One characteristic commonly used to group chipsets is the socket type of the processor. • Chipsets for Intel processors fit nicely into this grouping scheme, but chipsets from other manufacturers, such as ALi Corporation, NVIDIA Technologies, Silicon Integrated Systems Corporation (SiS), or VIA Technologies, Inc., do not always fit into this grouping scheme.

6. Grouping chipsets • North Bridge and South Bridge • The number of chips in the chipset is another characteristic used to group chipsets. • Chipsets can consist of one, two, or more chips. • The most common grouping is chipsets with two chips. (Northbridge and Southbridge) • However, manufacturers such as SiS and VIA produce mostly single chipsets today. Chipsets can contain as many as six chips.

7. Grouping chipsets • TAKING THE NORTH BRIDGE • The North Bridge chip contains the major bus circuits that provide support and control for main memory, cache memory, the Peripheral Component Interconnect (PCI), and the Accelerated Graphics Port (AGP) buses. • MOVING OVER TO THE SOUTH BRIDGE • The South Bridge includes controllers for peripheral devices and those controllers that are not a part of the PC’s basic functions, such as the Integrated Device Electronics/AT Attachment (IDE/ATA) and Enhanced IDE (EIDE) controllers and the serial port controllers.

8. Grouping chipsets

9. Digging deeper into the chipset • In general terms, a chipset contains circuitry to provide controller functions and bus architecture support. • Without going overboard, here is a brief overview of these chipset activities: • Controller chips: • The controller functions in a chipset control the transfer of data to and from peripheral devices by interfacing with the device controllers.

10. Digging deeper into the chipset • Bus architectures: • Because they control the flow of data to and from peripheral devices, device controllers must be matched to the bus architecture of the motherboard. • The motherboard’s bus architecture is made up of traces, wires, connectors, and devices over which data and instructions travel around the PC. • Most of the newest motherboard designs include expansion slots for a variety of bus and interface structures, including PCI, the AT bus, and possibly SCSI.

11. Digging deeper into the chipset • Bus architectures: • Because they control the flow of data to and from peripheral devices, device controllers must be matched to the bus architecture of the motherboard. • The motherboard’s bus architecture is made up of traces, wires, connectors, and devices over which data and instructions travel around the PC. • Most of the newest motherboard designs include expansion slots for a variety of bus and interface structures, including PCI, the AT bus, and possibly SCSI.

12. Digging deeper into the chipset • A few of the controllers and devices typically included in a chipset are • Memory controller • EIDE controller • PCI bridge • Real-time clock • Direct memory access (DMA) controllers • IrDA (Infrared Data Association) • Keyboard controller • PS/2 mouse controller • Secondary (Level 2) cache controller • CMOS SRAM

13. Digging deeper into the chipset • Knowing Which Bus to Take • The following sections give overviews of many of the bus and interface structures supported by most of the popular chipsets. • AT Bus • The AT bus is included on most chipsets primarily to provide support for expansion cards, such as network adapters, from older systems. • The AT bus runs at 8 MHz and uses a 16- bit data path. • It is commonly referred to as Industry Standard Architecture (ISA). Also includes EISA(Extended).

14. Digging deeper into the chipset • Local bus • A local bus device, which provides for very fast data transfers, is local to the processor through a dedicated controller that bypasses the standard bus controller. • PCI and Video Electronics Standards Association (VESA) local buses (VL-bus) are the most common of the local bus structures. • SCSI bus • SCSI (pronounced skuz-zee) attaches peripheral devices to a PC through a dedicated controller card that’s able to support a chain of devices over a dedicated interface structure and provides very fast data transfers

15. Digging deeper into the chipset • USB and IEEE 1394 • The Universal Serial Bus (USB) and the IEEE 1394 interfaces (such as Apple’s FireWire and Texas Instrument’s Lynx) are emerging standards for device connectors and interfaces. • USB and 1394 are Plug and Play (PnP) architectures that allow users to add a wide range of peripheral devices to the PC without the need of an adapter board. • IrDA and infrared • Bluetooth

16. Operating outside of the chipset • Typically, one or more device controller functions are kept outside of the chipset. • The primary reason for excluding them from the chipset is their volume of activity— some controller functions are usually quite busy. • Another reason for keeping them outside the chipset is that doing so provides better space economy on the chipset as well as on the motherboard. • Here are some device controller chips that might be kept outside of the chipset:

17. Operating outside of the chipset • Super I/O controller chip: • This discrete IC incorporates the functions that control the standard input/output devices and ports found on virtually every PC. • Included in the functions on a Super I/O chip are • Serial ports • Parallel ports • Floppy disk drives • Miscellaneous functions

18. Operating outside of the chipset • Keyboard controller • The keyboard controller controls the transfer of data from the keyboard to the PC. • The keyboard controller interacts with the controller located inside the keyboard over a serial link built into the connecting cable and connector. • The functions performed by the keyboard controller, or its equivalent, are • Keyboard control and translation • Support for the PS/2 mouse • Access to the HMA (High Memory Area)

19. Operating outside of the chipset • Other device controllers: • Every peripheral device on a PC that needs to interact with the data bus or the processor must have a device controller. • The very first PCs had an individual chip to control each of its peripheral or internal device functions, most of which are now embedded in chipsets, including • Math co-processor interface, Clock generator, Bus controller chip, DMA controller, Programmable Peripheral Interface (PPI), Floppy disk controller (FDC), CRT controller and Universal asynchronous receiver/transmitter (UART).

20. Getting to know the chipset • The characteristics of a chipset can be grouped into six categories: host, memory, interfaces, arbitration, South Bridge support, and power management. • Host: The host processor to which the chipset is matched along with its bus voltage, usually Gunning Transceiver Logic Plus (GTL+) or Advanced Gunning Transceiver Logic Plus (AGTL+), and the number of processors the chipset will support • Interfaces: The type of PCI interface implemented and whether the chipset is AGP-compliant supports integrated graphics, PIPE (pipelining), or side band addressing (SBA).

21. Getting to know the chipset • Memory: The characteristics of the dynamic random access memory (DRAM) support included in the chipset, including the DRAM refresh technique supported, the amount of memory supported (in megabits usually), the type of memory supported, and whether memory interleave, ECC, or parity is supported. • Arbitration: The method used by the chipset to arbitrate between different bus speeds and interfaces. The two most common arbitration methods are Multi-Transaction Timer (MTT) and Dynamic Intelligent Arbiter (DIA).

22. Getting to know the chipset • South Bridge support: All Intel chipsets and most of the chipsets for all other manufacturers are two processor sets. In these sets, the North Bridge is the main chip and handles CPU and memory interfaces among other tasks, and the South Bridge handles the USB and IDE interfaces, the real-time clock (RTC), and support for serial and parallel ports. • Power management: All Intel chipsets support both the System Management Mode (SMM) and Advanced Configuration and Power Interface (ACPI) power management standards.