What is a Computer?An electronic device that stores, retrieves andprocesses data, and can be programmed withinstructions.A computer is composed of hardware and software, and canexist in a variety of sizes and configurations.
Hardware & SoftwareThe term hardware refers to the Physicalcomponents of your computer such as the systemunit, mouse, keyboard, monitor etc.The software is the instructions that makes thecomputer work. Software is held either on yourcomputers hard disk, CD-ROM,DVD or on a diskette(floppy disk) and is loaded (i.e. copied) from the diskinto the computers RAM (Random AccessMemory),as and when required.
Types of ComputersMini and Mainframe ComputersVery powerful, used by largeorganizations such an banks to control theentire business operation. Very expensive!Personal ComputersCheap and easy to use. Often used as stand-alone computers or in a network.
Processor Processor is the brain of your computerSome key conceptsClock : In a computer, clock speed refers to thenumber of pulses per second that sets the tempo forthe processor.Cache :A small but fast memory area. Levels of cache exists.32/64 bit processors: The amount of data a processor canprocess in a clock cycle.
Two major vendersDual Core,Quad Core , I3 , I5 , I7 X2, X3, X4,
RAM Random Access Memory. When the operating system loads from disk when you first switch on the computer, it is copied into RAM. TypesOlder Computers P4s DDRCurrent Computers DDR2New Computers DDR3 (Double Data Rate)
ROMRead Only Memory (ROM) as the name suggests is a special type ofmemory chip that holds software that can be read but not written to.A good example is the ROM-BIOS chip, which contains read onlysoftware. Often network cards and video cards also contain ROMchips.
Motherboard Themain circuit board which connects allthe device on a microcomputer; Also calledmain board or system board.
Front Panel Connections
Hard Disk Stores data in magnetic disk like mediumNon-volatile mass storage device.Has very high access time as compared to RAM (10-20 million ns).Very cheap as compared to RAM and so large in capacity. TypesIDE- Integrated Drive Electronics (or)ATA - Advanced Technology AttachmentSATA- Serial Advanced Technology Attachment
SATA DATA CableData CablesPower Connectors IDE To SATA Connector
Difference Between IDE & SATAInterface transfer up to 8.3MB/s for ATA-2 and up to 100MB/s (ATA-6).Transfer rates for Serial ATA begin at 150MB/s.Big advantage of SATA over ATA is the cabling andconnectors in provides easier routing and better air flow . Easier to install multiple SATA drivers where as in IDE it has an jumper setting makes Some difficult tasks when more drives connected at a time.
CardsVGA CardVGA –Video Graphics AdaptorA modern graphics card is a circuit board with memory and adedicated processor.Converts digital information into the pixels to display it on themonitor.
Inbuilt VGAOn board graphics accelerators share system memory.Resolution will be less when compare to external card.
Sound CardConverts digital data (bits) into analog sound wave and vice-versa Has jacks for speaker, microphone, line in, line out and joysticks
Network Interface CardConnects PC to LAN (Local Area Network).Speeds 10Mbps 100Mbps
USB Card: USB-Universal Serial Bus To connect larger number of USB Ports to computers
PortsSerial:Serial port “serializes” data.Monitors, Modems etc. use Serial port.Parallel:Bits transmitted in parallel.Used primarily for Printers. PS/2:Used to interface keyboards andpointing devices. Frees the serial port for other devices.
USBData transfer rate 12Mbps/480Mbps.Multiple devices supported on the busHot pluggable, Plug-and-play.Provide power through the cable.
Power Cable VGA Cable Network CableUSB Cable
BIOSBasic Input Output SystemUses for boot upImportant FunctionsCheck CMOS Set-up. POST - Power On Self Test. Display system setting. Initiate bootstrap sequence.
Configuring BIOS System Time/Date.Boot Sequence.Plug and Play.Drive Configuration.Security.Power Management
Non-impact Printer InkjetThermalLaserAdv : Quiet, Can handle graphics, Varieties of fonts.Disadv. : Expensive.
ModemsInternal Modem Resides on the expansion board on the slot of the motherboard. Does not require separate power adapter.Cheaper than external modem.Has natural protection inside PC cabinet
External ModemResides on a self-contained box outside the PC.Requires external power adapter. Connected to PC’s serial port via the cable.Easy to install and troubleshoot such as resetting the modem. Expensive than internal modems.
Cabinet TypesAT CasesATX CasesAT Cases Older Motherboards (pre-pentium) Advantages Well Established standard make. Easy and cheap design. Disadvantages Inefficient cooling. Not suitable for P-II (& higher).
ATX CasesNewer Motherboards (Pentium based machine)AdvantagesEfficient cooling.Easy accessibility for upgrades.I/O are fixed onboard.
SMPSSwitched-Mode Power SupplyUsed to Power Supply for the components
Troubleshooting• Some simple solutionsCheck connections.Ensure that cards are inserted properly.Clean the devices.Check if minimum things needed to boot are present –motherboard, processor, a full bank of memory, video card and adrive to boot.
The PC doesn’t start at all Count the number of beeps. No beeps - possible problem with BIOS or motherboard.The PC starts - partiallyNo signal on the monitor.Video signal present with error message. OS starts. OS does not start - Hard-disk problem.
Hard Drive– Not bootable : A Hard Drive must be formatted and partitioned before it can be used.– Not detected by the BIOS - Check on a different m/c. It works fine. It does not work.