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Motherboards. Overview. In this chapter, you will learn to Explain how motherboards work Identify the types of motherboards Explain chipset varieties. Motherboard. Provides foundation for PC Every piece of H/W , from CPU to expansion card directly Example?
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Overview • In this chapter, you will learn to • Explain how motherboards work • Identify the types of motherboards • Explain chipset varieties
Motherboard • Provides foundation for PC • Every piece of H/W , from CPU to expansion card • directly Example? • or indirectly plugs into it. Example?
Motherboard • Motherboards are officially printed circuit boards (PCBs) • PCBs come in multiple layers with highways of wires (bus systems) in the layers • These highways of wires are called traces • Holds the vast majority of the ports used by peripherals • and it distributes powers from power supply .
Motherboard Characteristics • Three interrelated characteristics define modern motherboards : • Form Factor defines • Physical Size of the motherboard. • General location of components and parts. • Chipset defines • Type of processor and RAM supported. • Determine the internal and external devices supported by the motherboard. • Built-in components • Determine the core functionality of the system.
Form Factors • Industry standardized shapes and layouts that enable motherboards to work with cases and power supplies. • A single form factor applies to all 3 components (motherboard, power supply, and case). • You need to install a motherboard in a case designed to fit it, so ports and slot opening in the back fit correctly • Power supply and motherboard need • matching connectors.
Form Factors • The PC industry construct a number of form factors over the years with name such as: • AT • ATX • BTX • And others.
AT Form Factor • Used P8 and P9 connectors to power the motherboard • Single keyboard DIN or (PS\1) connector • Lack of external ports • Distinguished by position of the keyboard plug and power socket • Now: obsolete • Has a few size variations: • Baby AT is the most common (Pentium) • Full AT • LPX and NLX.
Baby AT Motherboard Single keyboard DIN connector Lack of external ports Power supply connector Small size
ATX Form Factor • Created in 1995 • Improves four main areas over AT. • Replace DIN port in AT with rear panel that has all necessary ports built in. • Better air movement • Easier access of RAM and CPU • Enhanced performance: by placing RAM closer to Northbridge and CPU. • Uses soft power to turn PC on/off through software.
ATX Form Factor • Uses Single 20-pin P1 power connector instead of P8 and P9. • Variations (smaller versions of ATX): • Micro ATX • and Flex ATX. • Many techs and web sites use the term mini-ATXto describe these boards
ATX Form Factor • Each main type of form factor requires its own cases. • AT Motherboard go into AT cases. • NLX Motherboard go into NLX cases. • Therefore, you can not replace one form factor with another without purchasing a new case. • Exception: larger form factor ATX cases can handle any smaller-sized form factor motherboard.
System Board (Pentium) Baby AT: 1- PS connector. 2- single DIN 3- Size
System Board (Pentium II) ATX: 1- PS connector. 2- rear panel
BTX Form Factor • BTX (Balanced Technology Extended) • Due to heat, cooler form factors needed • Three subtypes of BTX • BTX designed to replace ATX • microBTX designed to replace microATX • picoBTX designed to replace FlexATX • Its look like ATX but you can not put a BTX motherboard in an ATX case. Why? • BTX does not change the power connection, so there is no such thing as a BTX power supply.
BTX Form Factor & Thermal Unit CPU moved to front of Motherboard
The Chipset • Serves as electronicinterfaces through which the (CPU, RAM, and input/output devices) interact. Like what? • Several Chipset Varies in feature, performance and stability. • Composed of : • Northbridgehighspeed interfaces like video card RAM • and Southbridgelowspeed devices such as USB controller and hard drive controller keyboard controller. RAM Chipsets CPU I/O
The Chipset • Northbridge: • Helps the CPU work with RAM and video (on Intel-based systems). • Communicates with video card on newer AMD systems. Why? • Therefore they do a lot and get hot so they get their own heat sink and fan assembly. • Southbridge: • handles some expansion devices and mass storage drives. • Don’t need extra cooling. • Modern Southbridge do not support old devices (floppy drive, parallel port, modem,..). A third chip called Super I/O chip (not part of chipset) handle them.
The Chipset • Not always called Northbridge and Southbridge • Intel-based motherboards may refer to them as: • Memory Controller Hub (MCH) for Northbridge • and I/O Controller Hub (ICH) for Southbridge.
The Chipset • The system ROM chip provides part of the BIOS for the chipset. It is not sufficient. • You have to load the proper drivers for the specific OS to support all features of today’s chipsets. • All motherboard ship with a CD-ROM disc with drivers.
Chip Set Manufacturers • Some of the companies produce chipset designed for both Intel and AMD CPUs whereas others choose one or the other company to support. • Intel Corporation • AMD, Inc. • VIA Technology, Inc. • NVDIA corporation • SiS
How it all connects together Pentium CPU backside bus L2 Cache (in the CPU housing – on die) frontside bus L1 cache 32 bit address bus 64 bit data bus The Chipset extends the bus to every device on the PC. North Bridge (Memory Controller) AGP RAM AGP bus memory bus scanner HDD South Bridge PCI modem EIDE PCI bus sound CD/DVD ISA bus keyboard FDD ISA mouse BIOS
Motherboard Components • Connections and capabilities of a motherboard sometimes differ from its chipset. How? • Not all chipset features may be supported with ports (for cost savings) • Also a motherboard maker may choose to install extra features • USB / FireWire page 237 (exercise) • Sound page 238 (exercise) • RAID page 238 (exercise) • AMR/CNR page 238 (exercise)
Overview • In this chapter, you will learn to • Explain Read Only Memory • Explain the function of BIOS • Distinguish among various CMOS setup utility options • Describe BIOS and device drivers
What is (ROM)? • Read Only Memory • Memory chips that contain data, instructions, or information that is recorded permanently. • Data can only be read, cannot be modified • Nonvolatile — Contents not lost when the computer is turned off • Program stored on ROM are known as firmwarenot a Software.
ROM have different type: • ROM • PROM • Programmable Read-Only Memory (only once) • Blank ROM on which you can place items permanently • EPROM • Erasable PROM by Ultraviolet (every time you want) • EEPROM • Electrically Erasable PROM • A type of PROM containing microcode that a programmer can erase using electricity. Read Only Memory (ROM)
Variation of EEPROM • Also called flash ROM or flash RAM • Nonvolatile memory that can be erased electronically and reprogrammed. • Stores data and programs on many handheld computers and devices such as Camera and mobile phone. • Flash memory cards store flash memory on removable devices instead of chips What is Flash Memory?
We Need to Talk Placing a number of components into a computer is useless if CPU can not communicate with them.
Northbridge & Southbridge • Bridges (North, South) connect the devices • CPU uses address bus to talk to devices • But , How does it know what to say to them? Keyboard controller chip
Basic Input Output Services • A special kind of Program is required to enable the CPU to talk to other devices • These programs are collectively known as the basic input/output service (BIOS) • A Flash ROM chip stores these programs Why? • When CPU wants to talk to KB controller, it goes to BIOS ROM chip to access the proper program. Similar to codebook
BIOS • Basic Input Output Services • Permanently stored on ROM chip called System ROM or System BIOS • Contains small programs - each program is called a service- that enable CPU to • Communicate with the devices (keyboard, floppy, hard drive, monitor, …) • They are necessary to start the computer • load the operating system • and other files when you first turn on the computer
ROMBIOS • There is One ROM chip on the system board that contains BIOS. • Modern motherboards use Flash ROM (you can change the contents through a very specific process called “flashing the ROM”) Read about it in book P180 • There exists hundreds of little services (2 to 30 lines of code each)for communicating with floppy drives, hard drives, …
SystemBIOS • ROM chips can store 2 MB although only 65,536 bytes system are used to store system BIOS. • Every system BIOS has two types of hardware to support. • First: • All hardware that never changes. • Ex: KB, PC speaker. • You cannot change keyboard controller chip. • Second: • All hardware that might change. • Ex: RAM (you could add RAM), hard drives (replacing/ adding). • The system ROM stores the BIOS for them, but it needs another place to store information about the specific details of them CMOS
CMOS • A separate memory chip, called Complementary Metal-Oxide Semiconductor (CMOS) chip stores the information that describes specific device parameters. • CMOS does not store programs, only data that is read by BIOS to be able to talk to the changeable hardware. • CMOS also acts as a clock to keep date and time • Years ago: CMOS was in separate chip. • Today: CMOS is built into Southbridge.
CMOS • CMOS can store up to 64KB of data but usually only uses about 128 bytes • CMOS chip is volatile(kept alive by battery). This way the information contained in the CMOS are always present even if the computer power is turned off.
CMOS • Stores only changeable data. • Customizable via SETUP program. • If data in CMOS about certain hardware is different from its actual specs, PC can notaccess that hardware. • If you change one of changeable devices, parameters have to be changed in CMOS how to change data on CMOS?
CMOS SETUP Program • Special program that allows you to access and update CMOS data • Stored on system ROM (BIOS) • Companies that write the BIOS and how to access CMOS at boot: • Phoenix Technologies - Ctrl Alt Esc • Award Software - uses DEL key • American Megatrends (AMI) - DEL key • Other key combinations are: Ctrl Alt Ins, Ctrl A, Ctrl S, Ctrl F1, or F10
CMOS setup program • Exercise: how to access CMOS setup on your PC and what are the available options? • Caution: it is perfectly fine to access the CMOS setup program, but do not make changes unless you fully understand the system
BIOS and device drivers • PC designers understood that they could not anticipate every new type of H/W. • Therefore, they gave us ways to add programs for new devices other than on the BIOS. It is called BYOB(Bring Your Own BIOS) • Ex: Mice, Sound cards,…. • Two ways to BYOB: • Option ROM (hardware solution) • and device driver (software solution)
Option ROM • Embedded the BIOS in a ROM on the hardware device itself. • Today only video card contains its own BIOS. • Most devices use more flexible software method (device derivers).
Device drivers • A device driver is a file that contains the BIOS commands necessary to communicate with the devices they support stored on the PC’s hard drive. • Operating system loads these drivers into RAM when booting • They come with the device - in a CD- when you buy it. • The generic name for CD is installation disc
Registry • A special database –used by windows- that stores everything you want to know about your system, including device drivers. • Use device manager utility to access registry. You can manually change/remove and drivers • Exercise: how to use device manager?
