PC AssemblyPC Repair and Troubleshooting

Components & Devices Power Supply – Provides electricity Processor – Executes instructions Memory – Store instructions Bus – Connects Processor to I/O channels Disks

and Display Disks – Storage of Info I/O Channels – Connects Bus to other devices Display – Outputs a user readable data IO Devices – for the users communication with

the computer

Power Supply Necessary to make the electronics work Converts AC to DC

Processor & Instructions

Decodes the instructions and decide what is needed to be done

Each instructions operates on 1 or more pieces of information, the operands of the instruction

The length of each instruction execution cycle determines the performance of the computero 4 GHz – 4 billion instructions per second

Factors that could affect the number of executable instructions per second:o Size of instructiono Size and location of operandso Time it takes for the memory to deliver the operand to the processoro Time it takes to manipulate the operands to complete the instructiono Time it takes to put the results where it belongs

Buses Wires that computer chips operate according to

protocol for the behaviour of chips Bus wires carry signals among the chips

o What the component should doo Address on where it should be doneo Information

Bus cycle moving of information from 1 place to another

Distinct buses:o Front side bus

• connects processor to chipset• responsible for joining the different buses together

• Intel / AMD designo Memory bus

• Connects chipset to memory modules• Single Data Rate / Double Data Rate

o Graphics bus• Accelerated Graphics Port

o Expansion bus• Connects chipset to Adapter Cards and IO buses• Peripheral Component Interconnect

Memory Memory location

o places to store numberso 1 byte , 1 value from 0 to 255o Unique address

Memory moduleo Memory chips – few bitso Capacity – number of bytes it can holdo Width – number of bits that can be accessed at a timeo Access time – interval from reading the number to the availability of

number for processor. Smaller access time means faster memory but not faster computer

o Recovery delay – time from transferring of data to start of next operation

o Cycle time – access time + recovery delay Bandwidth

o volume of information a memory can read and write per second

Disk Drives

Each disk platter has a flat circular shape, like a CD ranging from 1.8 to 5.25 inches.

The two surfaces of a platter are covered with a magnetic material. We store information by recording it magnetically on the platters called Digital

Recording. A read-write head ``flies'' just above each surface of every platter. The heads are attached to a disk arm that moves all the heads as a unit. The surface of a platter is logically divided into circular tracks, which are

subdivided into sectors.o Tracks and Spots

• The disk surface is divided into concentric tracks (circles within circles). • The thinner the tracks, the more storage. • The data bits are recorded as tiny magnetic spots on the tracks. • The smaller the spot, the more bits per inch and the greater the storage.

o Sectors• hold a block of data that is read or written at one time• Outer Tracks contains more sectors

The set of tracks that are at one arm position makes up a cylinder. When the disk is in use, a drive motor spins it at high speed to the right. Most

drives rotate 60 to 200 times per second.

Inexpensive but access is slower than memory Store inactive programs Capacity = total sectors * sector size (512) Performance

o Rotation rate – speed of disk platters turns to head. RPMo Access time – time it takes from the processor requests

to its availability. Positioning of heads over the cylinder.o Sustained transfer rate – how much data can be

transferred onto or off of the platters

IO Channels Connects disks to bus Connects other attached devices Receives requests from the processor over the

bus Rearrange the requests if needed Handed to the disk

Display Video Card is a memory with surrounding

electronicso Digital to analog converters – changes numbers to

signalso Display memory – contains the pixel numbero Graphics acceleration processoro Timing and Controlo AGP or PCI bus

Monitoro Requires three signals (red, green and blue)

IO Devices Input Devices – the instruction is coming from the

user to be received by the computer Output Devices – the receiver of the result is the

user

Tools for Assembly Screwdrivers – slotted and Philips from small to

medium Socket drivers – screw heads that fits hex drivers Pliers – Nose Pliers Flashlight Mirror Multimeter – failure diagnosis Soldering Iron – Repairing / Removing

components from circuit cards Thin Gloves – reduces static discharge

Do’s and Don’tsDo’s

assemble your PC on a clean, uncluttered FLAT surface. Tiles if possible.

use properly insulated tools to reduce the possibility of static discharge from your body. Plastic or rubber handles.

use an anti-static wrist band if you have one available to reduce the possibility of static discharge from your body.

use cable ties or zip ties to secure wires in the PC when doing cable management.

close up the case and cover the build in progress when you're not working on it.

take notes while building and write down questions you come up with.

take your time and make sure components are secured properly, and connected correctly. Refer to manuals, or installation materials if you have them on hand.

Don’ts assemble your PC on a couch, or a carpeted

floor, or a chair, cushion, etc.. Use of improper tools drag your feet across the carpet and touch

the case just because you get a kick out of static shocks. This WILL screw up the components.

Liquids, foods and magnetic tools are not allowed to be near the PC.

use masking tape to secure ANY wires or components in the case. Fire hazard

handle open circuit boards or touch capacitors or resistors more than you absolutely need to.

plug in your power supply while you're working inside the box.

drill holes in your components because you think you can secure them better that way with more screws.

modify connections to make them fit, or splice wires together to create your own connections (unless you are a trained and experienced computer or electronics engineer).

BIOS makes sure all the other chips, hard drives, ports and CPU

function together Role of BIOS:

o Check the Complementary Metal Oxide Semiconductor (CMOS) Setup for custom settings• CMOS Setup provides detailed information particular to your system and

can be altered as your system changeso Load the interrupt handlers and device drivers

• Interrupt handlers act as translators between the hardware components and the operating system

o Initialize registers and power managemento Perform the power-on self-test (POST) to make sure everything is

working properlyo Display system settingso Determine which devices are bootableo Initiate the bootstrap sequence

Configuring BIOS Setup

To enter the CMOS Setup, you must press a certain key or combination of keys during the initial start up sequenceo "Esc," "Del," "F1," "F2," "Ctrl-Esc" or "Ctrl-Alt-Esc“

Incorrect settings may keep your computer from booting Configuration Option:

o System Time/Date - Set the system time and dateo Boot Sequence - The order that BIOS will try to load the operating systemo Plug and Play - A standard for auto-detecting connected devices; should be set

to "Yes" if your computer and operating system both support ito Mouse/Keyboard - "Enable Num Lock," "Enable the Keyboard," "Auto-Detect

Mouse“o Drive Configuration - Configure hard drives, CD-ROM and floppy driveso Memory - Direct the BIOS to shadow to a specific memory addresso Security - Set a password for accessing the computero Power Management - Select whether to use power management, as well as set

the amount of time for standby and suspendo Exit - Save your changes, discard your changes or restore default settings

Installing OS and Software

Back up all user files if you're planning to perform a system recovery. Gather together all the installation CDs which came with your computer and with

the devices you have added to your computer. Ensure that your computer is set up to boot from the CD-ROM drive. Place the first CD for the operating system in the CD drive. Turn the computer off. Wait a full 30 seconds before turning it back on again.

Turn the computer back on, and follow the instructions on the screen to partition and format your hard drive.

Follow the instructions which appear on the screen Reconnect to the internet. Troubleshoot any problems with your installation by

visiting the software provider's support website. Install or reinstall your antivirus software and promptly download and install all

the definition updates. Navigate immediately to the update site of the operating system's manufacturer

and download all critical updates. Install the software for any additional devices which did not come with your

computer. Update the drivers for all of your devices. Check device manager to see which version of each driver you are using and check the date.