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Basic PC Maintenance, Upgrade and Repair

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1 Basic PC Maintenance, Upgrade and Repair
Motherboards Basic PC Maintenance, Upgrade and Repair Mods 1 & 2

2 Motherboard Basics Considered to be the most important element of a computer’s design All major components connect to and transmit data across the motherboard It is the communication center for input and output devices such as memory, CPU, keyboard, mouse, parallel port, serial port, monitor and network connection Also provides the connection points required by the fans, speakers, on/off switches, LED indicators and CMOS battery Provides a means for expanding and customizing the system by inserting expansion boards into slots provided as direct connections to the system bus architecture It is also referred to as the system board, main board, and planar board

3 Motherboard Construction
It provides a physical surface on which to mount electronic components such as resistors, capacitors, IC chips, slots and sockets It is a combination of insulating material and electronic circuit paths constructed of small conductors that run along the surface. These conductive paths are known as traces Traces provide the electrical circuit paths between all the different components mounted on the motherboard The traces provide a means of sending and receiving data between components, as well as providing voltage and current to low power devices Many of the thin conductors on the motherboard are grouped together to make up what is referred to as bus A bus is a collection of conductors that work together for a specific purpose

4 Bus Classifications There are many types of bus classifications such as data bus, control bus, memory bus, internal bus, I/O bus, address bus, local bus, and power bus Data Bus – Used to move data between components in groups of 8, 16, 32, or 64 bits. The amount of data that can be moved at one time is referred to as the bus width Control Bus – a bus which delivers command signals from the processor to other devices (i.e. hard disk, modem, etc.) Memory Bus – a bus that connects directly between the memory and the processor I/O Bus – a bus that connects the processor to the expansion slots (also referred to as expansion bus) Internal Bus – is actually part of the IC circuit inside the CPU Address Bus – A bus system that connects directly with the main memory module. It identifies where data is to be stored and retrieved

5 Bus Classifications Local Bus – a bus system that connects directly to the CPU and provides communications to high-speed devices mounted closely to it (also called the system bus) Power Bus – a bus system that sends electrical power for small consumption devices such as speakers, lights and switches A bus may also be a collection of bus types. For example, the local bus consists of power, data, control and memory bus lines. For this reason, the local bus has also been referred to as the system bus or memory bus. Intel calls the local bus the front side bus (FSB)

6 Expansion Card Slots Expansion card slots provide a quick and easy method of connecting devices directly to the motherboard bus system in order to modify or customize the computer Several types have evolved over the years ISA – Industry Standard Architecture. The oldest bus system found on motherboards. 16 bit bus width. MCA – Micro Channel Architecture. Made by IBM. 32 bit bus width. Because IBM wanted royalties, MCA became EISA EISA – Extended Industry Standard Architecture. Developed by Compaq, AST Research, Epson, HP, NEC, Olivetti, Tandy, Wyse, and Zenith Data Systems in response to IBM’s MCA. 32 bit bus width VESA – Video Electronics Standards Association. Higher data transfer rate than MCA or EISA. Became obsolete when CPU speeds increased

7 Expansion Card Slots PCI – Peripheral Component Interconnect. Provides a high speed bus structure needed for faster CPU’s. Original PCI bus speed was 33Mhz. It has now evolved to bus speeds around 533Mhz. AGP – Accelerated Graphics Port. Designed exclusively for video cards, especially 3-D graphic support. Is as close as possible to the CPU and RAM to allow higher data transfer rates.

8 Data Ports Serial Ports – connects to devices that transfer data one bit at a time over one electrical conductor. There is one conductor for transmit and one for receive Parallel Port – Introduced as a high speed data transfer port. Has changed quite a bit since. Transmits 8 bits simultaneously over 8 electrical conductors. Common parallel port devices are printers, scanners and faxes Used to be unidirectional only (data out only) Extended Capabilities Port (ECP) allowed bidirectional parallel data transfer (data in and out) USB – Universal Serial Bus, was designed to replace the existing variety of ports and expansion slots. The USB 2.0 can achieve data rates as high as 480Mbps. Carries data and commands on two twisted data lines

9 Mouse and Keyboard Ports
Data Ports Parallel Port LAN Port Mouse and Keyboard Ports USB Ports IEEE 1394 Port Serial Port Video Port Audio Ports

10 System Resources System resources are resources that must be assigned and made available for devices such as printers, modems, disk drives, a mouse, sound card, etc. The major system resources to consider are I.O port address Memory addresses IRQ’s DMA settings Memory Address Range is an assigned section of memory used as a temporary storage area for data before it is transferred I/O Port Address is assigned to a device for identification, for communication purposes Both are expressed as a range, and in hexadecimal notation (i.e. 02E8h – 02EFh)

11 System Resources IRQ Settings
Devices connected to a computer motherboard need the attention of the CPU The only way is through an orderly system of IRQ settings IRQ stands for Interrupt Request An IRQ literally interrupts the processes taking place in the CPU and requests that the processor pay attention to a specific device Types of interrupts Hardware - Interrupts physically wired to the computer bus Software – Interrupts programmed into the software that call for the CPU’s attention IRQ’s are prioritized. The lower the number, the higher the priority IRQ 0 is the system timer. It has the highest priority because it is responsible for the timing of all devices, including the CPU

12 System Resources DMA Channels
In early computers, the CPU controlled all devices and their functions. For example, when data is moved from floppy drive to RAM, each data bit would have to be transferred to the CPU, then from the CPU to the RAM. DMA allows the floppy disk to transfer all the data directly to the RAM without the involvement of the CPU DMA stands for Direct Memory Access A combination of hardware and software that allows certain system devices direct access to the memory. This speeds up the process by not bothering the CPU (bottlenecking). A DMA controller has 4 channels each, with two controllers per motherboard.

13 Chip Sets Earlier PC’s had may more individual components mounted on the motherboard They were eventually redesigned into units called chipsets Chipset – a name for the collection of electronic circuitry required to carry out certain common motherboard functions Communication between PCI and ISA bus Controlling DMA Directing IRQ’s Serve as temporary memory Commonly divided into two categories North Bridge – used to transfer and control higher data speed systems such as graphics and DVD hardware South Bridge – used to control the slower devices associated with the PCI and ISA buses

14 Plug and Play PnP is the automatic assignment of system resources such as DMA channels, interrupts, memory and port assignments Simply plug in a device and the system software automatically assigns the system resources To work properly, BIOS, hardware being installed, and the operating system must all support PnP technology In the past, physical jumpers and/or DIP switches had to be set on the hardware to identify IRQ settings and port addresses Windows 95 and beyond support PnP to different degrees, depending on the version and device drivers available

15 BIOS and CMOS BIOS – a read only memory (ROM) chip that contains a group of software programs written in machine language Machine language is a language that uses hexadecimal codes to write a program BIOS is designed to initiate three different activities: POST – Power On Self Test CMOS setup program (BIOS setup) Communications between the system hardware and operating system BIOS controls the sequence of boot devices Upgrading BIOS – modern PC’s use Flash BIOS. It is an EEPROM which is electrically erased and then reprogrammed using software available through the motherboard manufacturer’s Web site and an updated BIOS program file CMOS – A battery backed RAM chip that stores the BIOS setup information

16 POST Short for Power On Self Test
A simple diagnostic program that is initiated at system power turn on It verifies that the major computer components are installed and in working order Typical devices checked are: CPU, ROM, RAM, keyboard, monitor, mouse, and hard drive It is not as sophisticated as diagnostic software, but it will check for major problems When finished, usually one “beep” is heard to let the user know everything is in working order If error is detected, an error code is displayed and a series of beeps are heard that match the code Error and beep codes can be obtained from the manufacturer’s Web site

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