Motherboards Chapter 7

How Motherboards Work The motherboard determines the function, expansion, and stability of the PC Form Factors Industry-standardized shapes and layouts Plays a big part in air flow. Must match the case and power supply. AT Form Factor Came out in the IBM PC/AT LPX – low profile extended NLX Riser slot for daughterboard ATX Form Factor Figure 7-7 No AT keyboard port microATX FlexATX ITX Mini-ITX, Nano-ITX, Pico-ITX Proprietary Form Factors

How Motherboards Work Chipset Northbridge Southbridge Super I/O chip Dealt with CPU, RAM, and video card Fast, frontside bus Southbridge Handles expansion bus and mass storage devices Super I/O chip Figure 7-13 ROM Hold BIOS Newer Terminology Memory Controller Hub (MCH) I/O Controller Hub (ICH)

How Motherboards Work Motherboard Components USB/FireWire Sound RAID Redundant array of independent disks Mirror or striping AMR/CNR Audio modem riser Communications and network riser Case Fan Support

Expansion Bus Structure and Function of the Expansion Bus PCI AGP Figures 7-20, 7-21, 7-22 Expansion bus crystal PCI Peripheral Component Interconnect 32 bits wide at 33 MHz PnP devices Burst mode AGP Accelerated Graphics Port Direct connection to Northbridge PCI-X PCI eXtended 64 bits wide at 66, 133, 266, and 533 MHz Mini-PCI Figure 7-29 PCI Express Point-to-point serial communications No bus sharing 2.5 Gbps or 5.0 Gbps per lane