PC Assembly - Lecture notes 7 PDF

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PC Assembly : A PC is a modular type of computer that can be assembled using hardware components made by different manufacturers. This allows you to have a custom-built computer that matches your specific needs.

Computer Assembly : The following components are available when building a computer: the casing, the motherboard, the processor, the RAM modules, the storage drives, and expansion cards. The metal casing houses the internal components of the computer. It usually comes with its own power supply and a set of screws, connectors, and cables. The processor is the computer's main integrated circuit and is known as the true brain of the computer, performing all of the main calculations. Storage devices, such as hard drives, CD-ROM, and DVD-ROM drives and burners as well as the floppy disk drive make it possible to store information on your PC. Expansion cards are used to upgrade computer functionality and performance.

The motherboard is a large printed circuit board used to connect the processor, RAM, hard drives, CD/DVD drives, and expansion cards. It comes with its own set of riser connectors:

PC Motherboard : The Motherboard is one of the basic and fundamental component of any computer system. It connects all the other components through different pathways or connections and it acts as a nervous system of the computer. It can be also called system board or main board. Motherboard is basically a PCB (Printed Circuit Board) on which all other components are attached

integratedly or physically through the wires and cables. Nowadays fully integrated motherboards are available in the market. The motherboard itself is a combinations of different components and some of the basic components of the motherboard are following  Form factors  Chipsets  Processor sockets  Memory slots  Expansion slots  Disk Connectors  Power connectors  BIOS/firmware  CMOS and CMOS battery  Back-panel connectors  Front-panel connectors

Form Factor The design classifications of the motherboard is called a form factor. The design classifications are basically the sizes and shapes (aka Dimensions) of the motherboard. There are huge number of form factors available today and only a motherboard having a specific form factor can be mounted on the

respective system’s case/body. The common form factors used nowadays are following  ATX (Advanced Technology Extended)  Micro ATX  ITX (Information Technology Extended ITX is a collection of SFF (Small form factor) boards. Baby AT was designed and made by the IBM and ATX is made by Intel.

Different form factors

Chipsets The chipset of the motherboard is a collection of chips and circuits that perform interface and peripheral functions for the processor. This collection of chips provides interfaces for memory, expansion cards, and on-board peripherals and

generally prescribes how a motherboard will communicate with the installed peripherals. Chipsets are usually given a name and model number by the original manufacturer like Intel’s X79. There are further two kinds of functional groups in chipsets, the first is Northbridge and the second is Southbridge . The Northbridge provides communication between the high speed components like Processor and memory or integrated video while the Southbridge provides the communication between the slower peripherals like PS/2, parallel ports and serial ports etc.

Northbridge and Southbridge architecture on chipset

Processor Sockets CPU sockets or slots are used to handle or fix the processor in motherboard. There are different sizes of the processor sockets depending upon the processor. Sockets are basically flat and have several columns and rows of holes or pins arranged in a square. There are further two types of sockets, one is pin grid array (PGA) and the other is land grid array (LGA). PGA sockets have holes, and the processors

have pins that fit into the holes. LGA sockets have contacts or pins which connect with contacts on the CPU. Mainly LGA sockets are mainly used today because there is a less chance of damaging of the processor because the pins are built in the sockets not in the processor.

PGA Processor Socket

LGA Processor Socket

Memory Slots Memory slots are used for holding memory chips that make up primary memory that is used to store currently used data and instructions for the CPU and that primary memory is also called RAM (Random Access Memory). Memory for desktops comes on circuit boards called dual inline memory modules (DIMMs) and for laptops on small outline DIMMs (SODIMMs). Memory slots are long and slender type and generally close to the CPU socket. They are available in different colors and mostly in white color.

Memory slots for DIMMs

Expansion Slots Expansion slots are used to install various devices in the computer to expand its capabilities and performance. Some expansion devices that can be installed in these slots include video card, network card, sound card, and disk interface cards. The expansion slots have further three types which are using today and that slots are:  PCI (Peripheral Component Interconnect) slots are usually 32 bits slots, 3 inches long that are mostly in white color.  AGP (Accelerated Graphic Port) slots are used for handling the video graphics card and they are mostly in brown color and they are slightly shorter than the PCI slots.  PCIe ( Peripheral Component Interconnect Expense) slots are the modern and usually faster than PCI and AGP and are mostly used today. These are found in different sizes. The following figure shows the different expansion slots and notice their color and sizes.

Different Expansion slots

Disk Connectors Motherboards have Disk Connectors that are used for connecting the hard drive which is permanent storing device. There are a few different kinds of hard drive connectors available today. One is Integrated Drive Electronics (IDE) connector or Parallel Advanced Technology Attachment (PATA) which is older one. The other one is Serial ATA (SATA) which is newer and much faster than PATA. PATA has large number of pins while SATA doesn’t have any pin.

SATA and PATA Connectors on Motherboard

Power Connectors Motherboard require electricity for functioning and it has a special 24-pin block connector that allows the motherboard to be connected to the power supply to receive power. This connector is where the ATX power adapter plugs in.

ATX 24-pin Power connector

BIOS/Firmware Firmware is a kind of software that is encoded in hardware like ROM (Read only memory), and can be run without extra instructions from the operating system. BIOS (Basic Input/Output System) is the one of the best example of firmware in a computer which is burned into a flash memory chip located on the motherboard. The BIOS chip is the second most important chip in the computer after the CPU and this chip contains the BIOS system software that boots the system and initiates the memory and hard drive to allow the operating system to start. BIOS chip can be recognized as it have on it the name of the manufacturer and usually the word BIOS as shown in the figure below with the manufacturer name AMI.

BIOS Chip on the motherboard

CMOS and CMOS Battery The CMOS stands for complementary metal oxide semiconductor and it is a special kind of chip technology used to store the basic information like date and time, hard drive configuration, memory and CPU settings, boot sequence, and power management features when the system is on or turned off. We can say that the chip is made through the CMOS technology and it has the BIOS settings saved on it.

The CMOS chip have a battery which is integrated near the chip on the motherboard and it is used to supply power continuously to the CMOS chip so that the BIOS settings are permanently stored. Normally, the CMOS battery is included next to the BIOS chip as shown in the figure below.

CMOS chip and the CMOS Battery

Back-Panel Connectors There are different types of connectors attached on the back of the motherboard which include power connector, video connector, audio connector, a

keyboard and mouse connectors, networking like Ethernet connector, and sometimes USB connectors.

Front-Panel Connectors There can also be different types of connectors attached on the front of the motherboard which include Power Button, Restart button, Audio ports for Microphone, headphones and speakers, and USB ports etc.

Various ports used in Computer : A port is a physical docking point using which an external device can be connected to the computer. It can also be programmatic docking point through which information flows from a program to the computer or over the Internet.

Characteristics of Ports A port has the following characteristics −

 External devices are connected to a computer using cables and ports.  Ports are slots on the motherboard into which a cable of external device is plugged in.  Examples of external devices attached via ports are the mouse, keyboard, monitor, microphone, speakers, etc.

Let us now discuss a few important types of ports −

Serial Port  Used for external modems and older computer mouse  Two versions: 9 pin, 25 pin model  Data travels at 115 kilobits per second

Parallel Port  Used for scanners and printers  Also called printer port  25 pin model  IEEE 1284-compliant Centronics port

PS/2 Port  Used for old computer keyboard and mouse  Also called mouse port  Most of the old computers provide two PS/2 port, each for the mouse and keyboard

 IEEE 1284-compliant Centronics port

Universal Serial Bus (or USB) Port  It can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc.  It was introduced in 1997.  Most of the computers provide two USB ports as minimum.  Data travels at 12 megabits per seconds.  USB compliant devices can get power from a USB port.

VGA Port  Connects monitor to a computer's video card.  It has 15 holes.  Similar to the serial port connector. However, serial port connector has pins, VGA port has holes.

Power Connector  Three-pronged plug.  Connects to the computer's power cable that plugs into a power bar or wall socket.

Firewire Port  Transfers large amount of data at very fast speed.  Connects camcorders and video equipment to the computer.  Data travels at 400 to 800 megabits per seconds.  Invented by Apple.  It has three variants: 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector, and 9-Pin FireWire 800 connector.

Modem Port  Connects a PC's modem to the telephone network.

Ethernet Port  Connects to a network and high speed Internet.  Connects the network cable to a computer.  This port resides on an Ethernet Card.  Data travels at 10 megabits to 1000 megabits per seconds depending upon the network bandwidth.

Game Port  Connect a joystick to a PC  Now replaced by USB

Digital Video Interface, DVI port  Connects Flat panel LCD monitor to the computer's high-end video graphic cards.  Very popular among video card manufacturers.

Sockets  Sockets connect the microphone and speakers to the sound card of the computer.

Connections in Computer : A connection is a term that describes the link between a plug or connector into a port or jack. For example, your monitor, mouse, and keyboard all must connect to the computer before they work. Below is a picture of the back of a desktop computer and each of the connections and ports. Although your desktop computer's

layout may be different, this diagram gives you a better understanding of where everything connects.

Below are related pages for each of the connections shown above and some related terms. Clicking on each of the links below allow you to get more information about these connections as well as related information.

Connections on the back of the computer  AT

 AUI  BNC  Composite  DisplayPort  DVI  eSATA  FireWire (IEEE-1394)  HDMI  M.2  MIDI  Modem (RJ-11 aka telephone)  Network (RJ-45)  PS/2 port  RCA  S-Video  S/PDIF  SCSI  Serial port (RS-232)

 Sound card (sound out or line out, sound in or line in, microphone, and MIDI (joystick).  Parallel port  USB  VGA/SVGA Connections on the back of a computer are color-coded so that users have a convenient way to locate the appropriate port for their peripheral device. The list below includes many ports and their associated colors.

 Keyboard (PS/2) - Purple  Mouse (PS/2) - Green  Serial - Cyan  Printer - Violet  Monitor (VGA) - Blue  Monitor (DVI) - White

 Line out (headphones) - Lime Green  Line in (microphone) - Pink  Audio in - Grey  Joystick – Yellow

Disassembling the computer system : Detach the power cable: The disassembling of the computer system starts with externally connected device detachment. Make sure the computer system is turned off, if not then successfully shut down the system and then start detaching the external devices from the computer system. It includes removing the power cable from electricity switchboard, then remove the cable from SMPS (switch mode power supply) from the back of the CPU Cabinet. Do not start the disassembling without detaching the power cable from the computer system. Now remove the remaining external devices like keyboard, mouse, monitor, printer or scanner from the back of CPU cabinet. Remove the Cover: The standard way of removing tower cases used to be to undo the screws on the back of the case, slide the cover back about an inch and lift it off. The screwdrivers as per the type of screw are required to do the task. Remove the adapter cards: Make sure if the card has any cables or wires that might be attached and decide if it would be easier to remove them before or after you remove the card. Remove the screw if any, that holds the card in place. Grab the card by its edges, front and back, and gently rock it lengthwise to release it. Remove the drives: Removing drives is easier. There can be possibly three types of drives present in your computer system, Hard disk drive, CD/DVD/Blue-ray drives, floppy disk drives (almost absolute now a day). They usually have a power connector and a data cable attached from the device to a controller card or a connector on the motherboard. CD/DVD/Blue Ray drive may have an analog cable connected to the sound card for direct audio output. The power may be attached using one of two connectors, a Molex connector or a Berg connector for the drive. The Molex connector may require to be wiggled slightly from side to side and apply gentle

pressure outwards. The Berg connector may just pull out or it may have a small tab which has to be lifted with a screwdriver. Now Pull data cables off from the drive as well as motherboard connector. The hard disk drive and CD/DVD drives have two types of data cables. IDE and SATA cables. The IDE cables need better care while being removed as it may cause the damage to drive connector pins. Gently wiggle the cable sideways and remove it. The SATA cables can be removed easily by pressing the tab and pulling the connector straight back. Now remove the screws and slide the drive out the back of the bay. Remove the memory module: Memory modules are mounted on the motherboard as the chips that can be damaged by manual force if applied improperly. Be careful and handle the chip only by the edges. SIMMs and DIMMs are removed in a different way: 

SIMM - gently push back the metal tabs while holding the SIMM chips in the socket. Tilt the SIMM chip away from the tabs until a 45% angle. It will now lift out of the socket. Put SIMM in a safe place.



DIMM- There are plastic tabs on the end of the DIMM sockets. Press the tabs down and away from the socket. The DIMM will lift slightly. Now grab it by the edges and place it safely. Do not let the chips get dust at all.

remove processor

remove the motherboard | Source

Remove the power supply: The power supply is attached into tower cabinet at the top back end of the tower. Make sure the power connector is detached from the switchboard. Start removing the power connector connected to motherboard including CPU fan power connector, cabinet fan, the front panel of cabinet power buttons and all the remaining drives if not detached yet. Now remove the screws of SMPS from the back of the cabinet and the SMPS can be detached from the tower cabinet. Remove the motherboard: Before removing all the connectors from the motherboard, make sure u memorize the connectors for assembling the computer if required, as that may require connecting the connectors at its place. Remove the screws from the back of the motherboard and you will be able to detach it from the cabinet. Now remove the CPU fan from the motherboard. The heat sink will be visible now which can be removed by the pulling the tab upward. Finally, the processor is visible now, which can be removed by the plastic tab which can be pulled back one stretching it side way....